Leskille/coding_challenge

1prob_desc_description,tags2"Consider some set of distinct characters $$$A$$$ and some string $$$S$$$, consisting of exactly $$$n$$$ characters, where each character is present in $$$A$$$.You are given an array of $$$m$$$ integers $$$b$$$ ($$$b_1 < b_2 < \dots < b_m$$$). You are allowed to perform the following move on the string $$$S$$$:  Choose some valid $$$i$$$ and set $$$k = b_i$$$;  Take the first $$$k$$$ characters of $$$S = Pr_k$$$;  Take the last $$$k$$$ characters of $$$S = Su_k$$$;  Substitute the first $$$k$$$ characters of $$$S$$$ with the reversed $$$Su_k$$$;  Substitute the last $$$k$$$ characters of $$$S$$$ with the reversed $$$Pr_k$$$. For example, let's take a look at $$$S =$$$ ""abcdefghi"" and $$$k = 2$$$. $$$Pr_2 =$$$ ""ab"", $$$Su_2 =$$$ ""hi"". Reversed $$$Pr_2 =$$$ ""ba"", $$$Su_2 =$$$ ""ih"". Thus, the resulting $$$S$$$ is ""ihcdefgba"".The move can be performed arbitrary number of times (possibly zero). Any $$$i$$$ can be selected multiple times over these moves.Let's call some strings $$$S$$$ and $$$T$$$ equal if and only if there exists such a sequence of moves to transmute string $$$S$$$ to string $$$T$$$. For the above example strings ""abcdefghi"" and ""ihcdefgba"" are equal. Also note that this implies $$$S = S$$$.The task is simple. Count the number of distinct strings.The answer can be huge enough, so calculate it modulo $$$998244353$$$.",['strings']3"This is the hard version of the problem. The difference is the constraint on the sum of lengths of strings and the number of test cases. You can make hacks only if you solve all versions of this task.You are given a string $$$s$$$, consisting of lowercase English letters. Find the longest string, $$$t$$$, which satisfies the following conditions:   The length of $$$t$$$ does not exceed the length of $$$s$$$.  $$$t$$$ is a palindrome.  There exists two strings $$$a$$$ and $$$b$$$ (possibly empty), such that $$$t = a + b$$$ ( ""$$$+$$$"" represents concatenation), and $$$a$$$ is prefix of $$$s$$$ while $$$b$$$ is suffix of $$$s$$$. ",['strings']4"You are a rebel leader and you are planning to start a revolution in your country. But the evil Government found out about your plans and set your punishment in the form of correctional labor.You must paint a fence which consists of $$$10^{100}$$$ planks in two colors in the following way (suppose planks are numbered from left to right from $$$0$$$):   if the index of the plank is divisible by $$$r$$$ (such planks have indices $$$0$$$, $$$r$$$, $$$2r$$$ and so on) then you must paint it red;  if the index of the plank is divisible by $$$b$$$ (such planks have indices $$$0$$$, $$$b$$$, $$$2b$$$ and so on) then you must paint it blue;  if the index is divisible both by $$$r$$$ and $$$b$$$ you can choose the color to paint the plank;  otherwise, you don't need to paint the plank at all (and it is forbidden to spent paint on it). Furthermore, the Government added one additional restriction to make your punishment worse. Let's list all painted planks of the fence in ascending order: if there are $$$k$$$ consecutive planks with the same color in this list, then the Government will state that you failed the labor and execute you immediately. If you don't paint the fence according to the four aforementioned conditions, you will also be executed.The question is: will you be able to accomplish the labor (the time is not important) or the execution is unavoidable and you need to escape at all costs.","['math', 'number theory']"5"Today, Wet Shark is given n bishops on a 1000 by 1000 grid. Both rows and columns of the grid are numbered from 1 to 1000. Rows are numbered from top to bottom, while columns are numbered from left to right.Wet Shark thinks that two bishops attack each other if they share the same diagonal. Note, that this is the only criteria, so two bishops may attack each other (according to Wet Shark) even if there is another bishop located between them. Now Wet Shark wants to count the number of pairs of bishops that attack each other.",[]6"Galya is playing one-dimensional Sea Battle on a 1 × n grid. In this game a ships are placed on the grid. Each of the ships consists of b consecutive cells. No cell can be part of two ships, however, the ships can touch each other.Galya doesn't know the ships location. She can shoot to some cells and after each shot she is told if that cell was a part of some ship (this case is called ""hit"") or not (this case is called ""miss"").Galya has already made k shots, all of them were misses.Your task is to calculate the minimum number of cells such that if Galya shoot at all of them, she would hit at least one ship.It is guaranteed that there is at least one valid ships placement.",['math']7"You are given two arrays A and B, each of size n. The error, E, between these two arrays is defined . You have to perform exactly k1 operations on array A and exactly k2 operations on array B. In one operation, you have to choose one element of the array and increase or decrease it by 1.Output the minimum possible value of error after k1 operations on array A and k2 operations on array B have been performed.",[]8"Egor wants to achieve a rating of 1600 points on the well-known chess portal ChessForces and he needs your help!Before you start solving the problem, Egor wants to remind you how the chess pieces move. Chess rook moves along straight lines up and down, left and right, as many squares as it wants. And when it wants, it can stop. The queen walks in all directions vertically and diagonally at any distance. You can see the examples below.  To reach the goal, Egor should research the next topic:There is an $$$N \times N$$$ board. Each cell of the board has a number from $$$1$$$ to $$$N ^ 2$$$ in it and numbers in all cells are distinct.In the beginning, some chess figure stands in the cell with the number $$$1$$$. Note that this cell is already considered as visited. After that every move is determined by the following rules:   Among all not visited yet cells to which the figure can get in one move, it goes to the cell that has minimal number. If all accessible cells were already visited and some cells are not yet visited, then the figure is teleported to the not visited cell that has minimal number. If this step happens, the piece pays a fee of $$$1$$$ vun. If all cells are already visited, the process is stopped. Egor should find an $$$N \times N$$$ board on which the rook pays strictly less vuns than the queen during the round with this numbering. Help him to find such $$$N \times N$$$ numbered board, or tell that it doesn't exist.",[]9"In Fire City, there are $$$n$$$ intersections and $$$m$$$ one-way roads. The $$$i$$$-th road goes from intersection $$$a_i$$$ to $$$b_i$$$ and has length $$$l_i$$$ miles. There are $$$q$$$ cars that may only drive along those roads. The $$$i$$$-th car starts at intersection $$$v_i$$$ and has an odometer that begins at $$$s_i$$$, increments for each mile driven, and resets to $$$0$$$ whenever it reaches $$$t_i$$$. Phoenix has been tasked to drive cars along some roads (possibly none) and return them to their initial intersection with the odometer showing $$$0$$$.For each car, please find if this is possible. A car may visit the same road or intersection an arbitrary number of times. The odometers don't stop counting the distance after resetting, so odometers may also be reset an arbitrary number of times.","['math', 'graphs', 'number theory']"10"Nikephoros and Polycarpus play rock-paper-scissors. The loser gets pinched (not too severely!).Let us remind you the rules of this game. Rock-paper-scissors is played by two players. In each round the players choose one of three items independently from each other. They show the items with their hands: a rock, scissors or paper. The winner is determined by the following rules: the rock beats the scissors, the scissors beat the paper and the paper beats the rock. If the players choose the same item, the round finishes with a draw.Nikephoros and Polycarpus have played n rounds. In each round the winner gave the loser a friendly pinch and the loser ended up with a fresh and new red spot on his body. If the round finished in a draw, the players did nothing and just played on.Nikephoros turned out to have worked out the following strategy: before the game began, he chose some sequence of items A = (a1, a2, ..., am), and then he cyclically showed the items from this sequence, starting from the first one. Cyclically means that Nikephoros shows signs in the following order: a1, a2, ..., am, a1, a2, ..., am, a1, ... and so on. Polycarpus had a similar strategy, only he had his own sequence of items B = (b1, b2, ..., bk).Determine the number of red spots on both players after they've played n rounds of the game. You can consider that when the game began, the boys had no red spots on them.",['math']11"There are $$$n$$$ students at your university. The programming skill of the $$$i$$$-th student is $$$a_i$$$. As a coach, you want to divide them into teams to prepare them for the upcoming ICPC finals. Just imagine how good this university is if it has $$$2 \cdot 10^5$$$ students ready for the finals!Each team should consist of at least three students. Each student should belong to exactly one team. The diversity of a team is the difference between the maximum programming skill of some student that belongs to this team and the minimum programming skill of some student that belongs to this team (in other words, if the team consists of $$$k$$$ students with programming skills $$$a[i_1], a[i_2], \dots, a[i_k]$$$, then the diversity of this team is $$$\max\limits_{j=1}^{k} a[i_j] - \min\limits_{j=1}^{k} a[i_j]$$$).The total diversity is the sum of diversities of all teams formed.Your task is to minimize the total diversity of the division of students and find the optimal way to divide the students.",[]12"Sherlock Holmes found a mysterious correspondence of two VIPs and made up his mind to read it. But there is a problem! The correspondence turned out to be encrypted. The detective tried really hard to decipher the correspondence, but he couldn't understand anything. At last, after some thought, he thought of something. Let's say there is a word s, consisting of |s| lowercase Latin letters. Then for one operation you can choose a certain position p (1 ≤ p < |s|) and perform one of the following actions:   either replace letter sp with the one that alphabetically follows it and replace letter sp + 1 with the one that alphabetically precedes it;  or replace letter sp with the one that alphabetically precedes it and replace letter sp + 1 with the one that alphabetically follows it. Let us note that letter ""z"" doesn't have a defined following letter and letter ""a"" doesn't have a defined preceding letter. That's why the corresponding changes are not acceptable. If the operation requires performing at least one unacceptable change, then such operation cannot be performed.Two words coincide in their meaning iff one of them can be transformed into the other one as a result of zero or more operations.Sherlock Holmes needs to learn to quickly determine the following for each word: how many words can exist that coincide in their meaning with the given word, but differs from the given word in at least one character? Count this number for him modulo 1000000007 (109 + 7).",[]13"Vasya plays one very well-known and extremely popular MMORPG game. His game character has k skill; currently the i-th of them equals to ai. Also this game has a common rating table in which the participants are ranked according to the product of all the skills of a hero in the descending order.Vasya decided to 'upgrade' his character via the game store. This store offers n possible ways to improve the hero's skills; Each of these ways belongs to one of three types:  assign the i-th skill to b;  add b to the i-th skill;  multiply the i-th skill by b. Unfortunately, a) every improvement can only be used once; b) the money on Vasya's card is enough only to purchase not more than m of the n improvements. Help Vasya to reach the highest ranking in the game. To do this tell Vasya which of improvements he has to purchase and in what order he should use them to make his rating become as high as possible. If there are several ways to achieve it, print any of them.",[]14"This is the second subtask of problem F. The only differences between this and the first subtask are the constraints on the value of $$$m$$$ and the time limit. It is sufficient to solve this subtask in order to hack it, but you need to solve both subtasks in order to hack the first one.There are $$$n+1$$$ distinct colours in the universe, numbered $$$0$$$ through $$$n$$$. There is a strip of paper $$$m$$$ centimetres long initially painted with colour $$$0$$$. Alice took a brush and painted the strip using the following process. For each $$$i$$$ from $$$1$$$ to $$$n$$$, in this order, she picks two integers $$$0 \leq a_i < b_i \leq m$$$, such that the segment $$$[a_i, b_i]$$$ is currently painted with a single colour, and repaints it with colour $$$i$$$. Alice chose the segments in such a way that each centimetre is now painted in some colour other than $$$0$$$. Formally, the segment $$$[i-1, i]$$$ is painted with colour $$$c_i$$$ ($$$c_i \neq 0$$$). Every colour other than $$$0$$$ is visible on the strip.Count the number of different pairs of sequences $$$\{a_i\}_{i=1}^n$$$, $$$\{b_i\}_{i=1}^n$$$ that result in this configuration. Since this number may be large, output it modulo $$$998244353$$$.",[]15"There are $$$n$$$ seats in the train's car and there is exactly one passenger occupying every seat. The seats are numbered from $$$1$$$ to $$$n$$$ from left to right. The trip is long, so each passenger will become hungry at some moment of time and will go to take boiled water for his noodles. The person at seat $$$i$$$ ($$$1 \leq i \leq n$$$) will decide to go for boiled water at minute $$$t_i$$$.Tank with a boiled water is located to the left of the $$$1$$$-st seat. In case too many passengers will go for boiled water simultaneously, they will form a queue, since there can be only one passenger using the tank at each particular moment of time. Each passenger uses the tank for exactly $$$p$$$ minutes. We assume that the time it takes passengers to go from their seat to the tank is negligibly small. Nobody likes to stand in a queue. So when the passenger occupying the $$$i$$$-th seat wants to go for a boiled water, he will first take a look on all seats from $$$1$$$ to $$$i - 1$$$. In case at least one of those seats is empty, he assumes that those people are standing in a queue right now, so he would be better seating for the time being. However, at the very first moment he observes that all seats with numbers smaller than $$$i$$$ are busy, he will go to the tank.There is an unspoken rule, that in case at some moment several people can go to the tank, than only the leftmost of them (that is, seating on the seat with smallest number) will go to the tank, while all others will wait for the next moment.Your goal is to find for each passenger, when he will receive the boiled water for his noodles.",[]16You are given two integers $$$n$$$ and $$$m$$$ ($$$m < n$$$). Consider a convex regular polygon of $$$n$$$ vertices. Recall that a regular polygon is a polygon that is equiangular (all angles are equal in measure) and equilateral (all sides have the same length).  Examples of convex regular polygons Your task is to say if it is possible to build another convex regular polygon with $$$m$$$ vertices such that its center coincides with the center of the initial polygon and each of its vertices is some vertex of the initial polygon.You have to answer $$$t$$$ independent test cases.,"['math', 'number theory', 'geometry']"17"This is an interactive problem.You're given a tree consisting of $$$n$$$ nodes, rooted at node $$$1$$$. A tree is a connected graph with no cycles.We chose a hidden node $$$x$$$. In order to find this node, you can ask queries of two types:   d $$$u$$$ ($$$1 \le u \le n$$$). We will answer with the distance between nodes $$$u$$$ and $$$x$$$. The distance between two nodes is the number of edges in the shortest path between them.  s $$$u$$$ ($$$1 \le u \le n$$$). We will answer with the second node on the path from $$$u$$$ to $$$x$$$. However, there's a plot twist. If $$$u$$$ is not an ancestor of $$$x$$$, you'll receive ""Wrong answer"" verdict! Node $$$a$$$ is called an ancestor of node $$$b$$$ if $$$a \ne b$$$ and the shortest path from node $$$1$$$ to node $$$b$$$ passes through node $$$a$$$. Note that in this problem a node is not an ancestor of itself.Can you find $$$x$$$ in no more than $$$36$$$ queries? The hidden node is fixed in each test beforehand and does not depend on your queries.","['graphs', 'trees']"18"You are given an array $$$a$$$ of length $$$n$$$, and an integer $$$x$$$. You can perform the following operation as many times as you would like (possibly zero): replace two adjacent elements of the array by their sum. For example, if the initial array was $$$[3, 6, 9]$$$, in a single operation one can replace the last two elements by their sum, yielding an array $$$[3, 15]$$$, or replace the first two elements to get an array $$$[9, 9]$$$. Note that the size of the array decreases after each operation.The beauty of an array $$$b=[b_1, \ldots, b_k]$$$ is defined as $$$\sum_{i=1}^k \left\lceil \frac{b_i}{x} \right\rceil$$$, which means that we divide each element by $$$x$$$, round it up to the nearest integer, and sum up the resulting values. For example, if $$$x = 3$$$, and the array is $$$[4, 11, 6]$$$, the beauty of the array is equal to $$$\left\lceil \frac{4}{3} \right\rceil + \left\lceil \frac{11}{3} \right\rceil + \left\lceil \frac{6}{3} \right\rceil = 2 + 4 + 2 = 8$$$.Please determine the minimum and the maximum beauty you can get by performing some operations on the original array.","['math', 'number theory']"19"Recently in Divanovo, a huge river locks system was built. There are now $$$n$$$ locks, the $$$i$$$-th of them has the volume of $$$v_i$$$ liters, so that it can contain any amount of water between $$$0$$$ and $$$v_i$$$ liters. Each lock has a pipe attached to it. When the pipe is open, $$$1$$$ liter of water enters the lock every second.The locks system is built in a way to immediately transfer all water exceeding the volume of the lock $$$i$$$ to the lock $$$i + 1$$$. If the lock $$$i + 1$$$ is also full, water will be transferred further. Water exceeding the volume of the last lock pours out to the river.   The picture illustrates $$$5$$$ locks with two open pipes at locks $$$1$$$ and $$$3$$$. Because locks $$$1$$$, $$$3$$$, and $$$4$$$ are already filled, effectively the water goes to locks $$$2$$$ and $$$5$$$. Note that the volume of the $$$i$$$-th lock may be greater than the volume of the $$$i + 1$$$-th lock.To make all locks work, you need to completely fill each one of them. The mayor of Divanovo is interested in $$$q$$$ independent queries. For each query, suppose that initially all locks are empty and all pipes are closed. Then, some pipes are opened simultaneously. For the $$$j$$$-th query the mayor asks you to calculate the minimum number of pipes to open so that all locks are filled no later than after $$$t_j$$$ seconds.Please help the mayor to solve this tricky problem and answer his queries. ",['math']20"On a number line there are n balls. At time moment 0 for each ball the following data is known: its coordinate xi, speed vi (possibly, negative) and weight mi. The radius of the balls can be ignored.The balls collide elastically, i.e. if two balls weighing m1 and m2 and with speeds v1 and v2 collide, their new speeds will be: .Your task is to find out, where each ball will be t seconds after.",['math']21"You are given a string s, consisting of small Latin letters. Let's denote the length of the string as |s|. The characters in the string are numbered starting from 1. Your task is to find out if it is possible to rearrange characters in string s so that for any prime number p ≤ |s| and for any integer i ranging from 1 to |s| / p (inclusive) the following condition was fulfilled sp = sp × i. If the answer is positive, find one way to rearrange the characters.","['strings', 'number theory']"22"You are given two integers $$$A$$$ and $$$B$$$, calculate the number of pairs $$$(a, b)$$$ such that $$$1 \le a \le A$$$, $$$1 \le b \le B$$$, and the equation $$$a \cdot b + a + b = conc(a, b)$$$ is true; $$$conc(a, b)$$$ is the concatenation of $$$a$$$ and $$$b$$$ (for example, $$$conc(12, 23) = 1223$$$, $$$conc(100, 11) = 10011$$$). $$$a$$$ and $$$b$$$ should not contain leading zeroes.",['math']23"Phoenix has decided to become a scientist! He is currently investigating the growth of bacteria.Initially, on day $$$1$$$, there is one bacterium with mass $$$1$$$.Every day, some number of bacteria will split (possibly zero or all). When a bacterium of mass $$$m$$$ splits, it becomes two bacteria of mass $$$\frac{m}{2}$$$ each. For example, a bacterium of mass $$$3$$$ can split into two bacteria of mass $$$1.5$$$.Also, every night, the mass of every bacteria will increase by one.Phoenix is wondering if it is possible for the total mass of all the bacteria to be exactly $$$n$$$. If it is possible, he is interested in the way to obtain that mass using the minimum possible number of nights. Help him become the best scientist!",['math']24"An integer array $$$a_1, a_2, \ldots, a_n$$$ is being transformed into an array of lowercase English letters using the following prodecure:While there is at least one number in the array:   Choose any number $$$x$$$ from the array $$$a$$$, and any letter of the English alphabet $$$y$$$.  Replace all occurrences of number $$$x$$$ with the letter $$$y$$$. For example, if we initially had an array $$$a = [2, 3, 2, 4, 1]$$$, then we could transform it the following way:  Choose the number $$$2$$$ and the letter c. After that $$$a = [c, 3, c, 4, 1]$$$.  Choose the number $$$3$$$ and the letter a. After that $$$a = [c, a, c, 4, 1]$$$.  Choose the number $$$4$$$ and the letter t. After that $$$a = [c, a, c, t, 1]$$$.  Choose the number $$$1$$$ and the letter a. After that $$$a = [c, a, c, t, a]$$$. After the transformation all letters are united into a string, in our example we get the string ""cacta"".Having the array $$$a$$$ and the string $$$s$$$ determine if the string $$$s$$$ could be got from the array $$$a$$$ after the described transformation?",[]25"After the lessons n groups of schoolchildren went outside and decided to visit Polycarpus to celebrate his birthday. We know that the i-th group consists of si friends (1 ≤ si ≤ 4), and they want to go to Polycarpus together. They decided to get there by taxi. Each car can carry at most four passengers. What minimum number of cars will the children need if all members of each group should ride in the same taxi (but one taxi can take more than one group)?",[]26"Polycarp found on the street an array $$$a$$$ of $$$n$$$ elements.Polycarp invented his criterion for the beauty of an array. He calls an array $$$a$$$ beautiful if at least one of the following conditions must be met for each different pair of indices $$$i \ne j$$$:   $$$a_i$$$ is divisible by $$$a_j$$$;  or $$$a_j$$$ is divisible by $$$a_i$$$. For example, if:   $$$n=5$$$ and $$$a=[7, 9, 3, 14, 63]$$$, then the $$$a$$$ array is not beautiful (for $$$i=4$$$ and $$$j=2$$$, none of the conditions above is met);  $$$n=3$$$ and $$$a=[2, 14, 42]$$$, then the $$$a$$$ array is beautiful;  $$$n=4$$$ and $$$a=[45, 9, 3, 18]$$$, then the $$$a$$$ array is not beautiful (for $$$i=1$$$ and $$$j=4$$$ none of the conditions above is met); Ugly arrays upset Polycarp, so he wants to remove some elements from the array $$$a$$$ so that it becomes beautiful. Help Polycarp determine the smallest number of elements to remove to make the array $$$a$$$ beautiful.","['math', 'number theory']"27"Vasya plays FreeDiv. In this game he manages a huge state, which has n cities and m two-way roads between them. Unfortunately, not from every city you can reach any other one moving along these roads. Therefore Vasya decided to divide the state into provinces so that in every province, one could reach from every city all the cities of the province, but there are no roads between provinces. Unlike other turn-based strategies, in FreeDiv a player has the opportunity to build tunnels between cities. The tunnels are two-way roads along which one can move armies undetected by the enemy. However, no more than one tunnel can be connected to each city. As for Vasya, he wants to build a network of tunnels so that any pair of cities in his state were reachable by some path consisting of roads and a tunnels. But at that no more than k tunnels are connected to each province (otherwise, the province will be difficult to keep in case other provinces are captured by enemy armies).Vasya discovered that maybe he will not be able to build such a network for the current condition of the state. Maybe he'll have first to build several roads between cities in different provinces to merge the provinces. Your task is to determine the minimum number of roads Vasya needs to build so that it was possible to build the required network of tunnels in the resulting state.",['graphs']28"Mr. Kitayuta has just bought an undirected graph consisting of n vertices and m edges. The vertices of the graph are numbered from 1 to n. Each edge, namely edge i, has a color ci, connecting vertex ai and bi.Mr. Kitayuta wants you to process the following q queries.In the i-th query, he gives you two integers — ui and vi.Find the number of the colors that satisfy the following condition: the edges of that color connect vertex ui and vertex vi directly or indirectly.",['graphs']29"Polycarpus has a hobby — he develops an unusual social network. His work is almost completed, and there is only one more module to implement — the module which determines friends. Oh yes, in this social network one won't have to add friends manually! Pairs of friends are deduced in the following way. Let's assume that user A sent user B a message at time t1, and user B sent user A a message at time t2. If 0 < t2 - t1 ≤ d, then user B's message was an answer to user A's one. Users A and B are considered to be friends if A answered at least one B's message or B answered at least one A's message.You are given the log of messages in chronological order and a number d. Find all pairs of users who will be considered to be friends.",[]30"You are given a directed graph of $$$n$$$ vertices and $$$m$$$ edges. Vertices are numbered from $$$1$$$ to $$$n$$$. There is a token in vertex $$$1$$$.The following actions are allowed:   Token movement. To move the token from vertex $$$u$$$ to vertex $$$v$$$ if there is an edge $$$u \to v$$$ in the graph. This action takes $$$1$$$ second.  Graph transposition. To transpose all the edges in the graph: replace each edge $$$u \to v$$$ by an edge $$$v \to u$$$. This action takes increasingly more time: $$$k$$$-th transposition takes $$$2^{k-1}$$$ seconds, i.e. the first transposition takes $$$1$$$ second, the second one takes $$$2$$$ seconds, the third one takes $$$4$$$ seconds, and so on. The goal is to move the token from vertex $$$1$$$ to vertex $$$n$$$ in the shortest possible time. Print this time modulo $$$998\,244\,353$$$.",['graphs']31"You are given a matrix $$$a$$$ of size $$$n \times m$$$ consisting of integers.You can choose no more than $$$\left\lfloor\frac{m}{2}\right\rfloor$$$ elements in each row. Your task is to choose these elements in such a way that their sum is divisible by $$$k$$$ and this sum is the maximum.In other words, you can choose no more than a half (rounded down) of elements in each row, you have to find the maximum sum of these elements divisible by $$$k$$$.Note that you can choose zero elements (and the sum of such set is $$$0$$$).",[]32"Limak is a little polar bear. He doesn't have many toys and thus he often plays with polynomials.He considers a polynomial valid if its degree is n and its coefficients are integers not exceeding k by the absolute value. More formally:Let a0, a1, ..., an denote the coefficients, so . Then, a polynomial P(x) is valid if all the following conditions are satisfied:  ai is integer for every i;  |ai| ≤ k for every i;  an ≠ 0. Limak has recently got a valid polynomial P with coefficients a0, a1, a2, ..., an. He noticed that P(2) ≠ 0 and he wants to change it. He is going to change one coefficient to get a valid polynomial Q of degree n that Q(2) = 0. Count the number of ways to do so. You should count two ways as a distinct if coefficients of target polynoms differ.",['math']33"A string is called a k-string if it can be represented as k concatenated copies of some string. For example, the string ""aabaabaabaab"" is at the same time a 1-string, a 2-string and a 4-string, but it is not a 3-string, a 5-string, or a 6-string and so on. Obviously any string is a 1-string.You are given a string s, consisting of lowercase English letters and a positive integer k. Your task is to reorder the letters in the string s in such a way that the resulting string is a k-string.",['strings']34"There is an undirected, connected graph with $$$n$$$ vertices and $$$m$$$ weighted edges. A walk from vertex $$$u$$$ to vertex $$$v$$$ is defined as a sequence of vertices $$$p_1,p_2,\ldots,p_k$$$ (which are not necessarily distinct) starting with $$$u$$$ and ending with $$$v$$$, such that $$$p_i$$$ and $$$p_{i+1}$$$ are connected by an edge for $$$1 \leq i < k$$$.We define the length of a walk as follows: take the ordered sequence of edges and write down the weights on each of them in an array. Now, write down the bitwise AND of every nonempty prefix of this array. The length of the walk is the MEX of all these values.More formally, let us have $$$[w_1,w_2,\ldots,w_{k-1}]$$$ where $$$w_i$$$ is the weight of the edge between $$$p_i$$$ and $$$p_{i+1}$$$. Then the length of the walk is given by $$$\mathrm{MEX}(\{w_1,\,w_1\& w_2,\,\ldots,\,w_1\& w_2\& \ldots\& w_{k-1}\})$$$, where $$$\&$$$ denotes the bitwise AND operation.Now you must process $$$q$$$ queries of the form u v. For each query, find the minimum possible length of a walk from $$$u$$$ to $$$v$$$.The MEX (minimum excluded) of a set is the smallest non-negative integer that does not belong to the set. For instance:   The MEX of $$$\{2,1\}$$$ is $$$0$$$, because $$$0$$$ does not belong to the set.  The MEX of $$$\{3,1,0\}$$$ is $$$2$$$, because $$$0$$$ and $$$1$$$ belong to the set, but $$$2$$$ does not.  The MEX of $$$\{0,3,1,2\}$$$ is $$$4$$$ because $$$0$$$, $$$1$$$, $$$2$$$ and $$$3$$$ belong to the set, but $$$4$$$ does not. ",['graphs']35"You are given a set Y of n distinct positive integers y1, y2, ..., yn.Set X of n distinct positive integers x1, x2, ..., xn is said to generate set Y if one can transform X to Y by applying some number of the following two operation to integers in X:  Take any integer xi and multiply it by two, i.e. replace xi with 2·xi.  Take any integer xi, multiply it by two and add one, i.e. replace xi with 2·xi + 1. Note that integers in X are not required to be distinct after each operation.Two sets of distinct integers X and Y are equal if they are equal as sets. In other words, if we write elements of the sets in the array in the increasing order, these arrays would be equal.Note, that any set of integers (or its permutation) generates itself.You are given a set Y and have to find a set X that generates Y and the maximum element of X is mininum possible.","['strings', 'trees']"36"You are given a string $$$s$$$ consisting of lowercase letters of the English alphabet. You must perform the following algorithm on $$$s$$$:  Let $$$x$$$ be the length of the longest prefix of $$$s$$$ which occurs somewhere else in $$$s$$$ as a contiguous substring (the other occurrence may also intersect the prefix). If $$$x = 0$$$, break. Otherwise, remove the first $$$x$$$ characters of $$$s$$$, and repeat. A prefix is a string consisting of several first letters of a given string, without any reorders. An empty prefix is also a valid prefix. For example, the string ""abcd"" has 5 prefixes: empty string, ""a"", ""ab"", ""abc"" and ""abcd"".For instance, if we perform the algorithm on $$$s =$$$ ""abcabdc"",   Initially, ""ab"" is the longest prefix that also appears somewhere else as a substring in $$$s$$$, so $$$s =$$$ ""cabdc"" after $$$1$$$ operation.  Then, ""c"" is the longest prefix that also appears somewhere else as a substring in $$$s$$$, so $$$s =$$$ ""abdc"" after $$$2$$$ operations.  Now $$$x=0$$$ (because there are no non-empty prefixes of ""abdc"" that also appear somewhere else as a substring in $$$s$$$), so the algorithm terminates. Find the final state of the string after performing the algorithm.",['strings']37"Little Masha loves arranging her toys into piles on the floor. And she also hates it when somebody touches her toys. One day Masha arranged all her n toys into several piles and then her elder brother Sasha came and gathered all the piles into one. Having seen it, Masha got very upset and started crying. Sasha still can't calm Masha down and mom is going to come home soon and punish Sasha for having made Masha crying. That's why he decides to restore the piles' arrangement. However, he doesn't remember at all the way the toys used to lie. Of course, Masha remembers it, but she can't talk yet and can only help Sasha by shouting happily when he arranges the toys in the way they used to lie. That means that Sasha will have to arrange the toys in every possible way until Masha recognizes the needed arrangement. The relative position of the piles and toys in every pile is irrelevant, that's why the two ways of arranging the toys are considered different if can be found two such toys that when arranged in the first way lie in one and the same pile and do not if arranged in the second way. Sasha is looking for the fastest way of trying all the ways because mom will come soon. With every action Sasha can take a toy from any pile and move it to any other pile (as a result a new pile may appear or the old one may disappear). Sasha wants to find the sequence of actions as a result of which all the pile arrangement variants will be tried exactly one time each. Help Sasha. As we remember, initially all the toys are located in one pile. ",[]38"Ivan has an array consisting of n different integers. He decided to reorder all elements in increasing order. Ivan loves merge sort so he decided to represent his array with one or several increasing sequences which he then plans to merge into one sorted array.Ivan represent his array with increasing sequences with help of the following algorithm.While there is at least one unused number in array Ivan repeats the following procedure:  iterate through array from the left to the right;  Ivan only looks at unused numbers on current iteration;  if current number is the first unused number on this iteration or this number is greater than previous unused number on current iteration, then Ivan marks the number as used and writes it down. For example, if Ivan's array looks like [1, 3, 2, 5, 4] then he will perform two iterations. On first iteration Ivan will use and write numbers [1, 3, 5], and on second one — [2, 4].Write a program which helps Ivan and finds representation of the given array with one or several increasing sequences in accordance with algorithm described above.",[]39"Let us define a magic grid to be a square matrix of integers of size $$$n \times n$$$, satisfying the following conditions.   All integers from $$$0$$$ to $$$(n^2 - 1)$$$ inclusive appear in the matrix exactly once.  Bitwise XOR of all elements in a row or a column must be the same for each row and column. You are given an integer $$$n$$$ which is a multiple of $$$4$$$. Construct a magic grid of size $$$n \times n$$$.",[]40"The busses in Berland are equipped with a video surveillance system. The system records information about changes in the number of passengers in a bus after stops.If $$$x$$$ is the number of passengers in a bus just before the current bus stop and $$$y$$$ is the number of passengers in the bus just after current bus stop, the system records the number $$$y-x$$$. So the system records show how number of passengers changed.The test run was made for single bus and $$$n$$$ bus stops. Thus, the system recorded the sequence of integers $$$a_1, a_2, \dots, a_n$$$ (exactly one number for each bus stop), where $$$a_i$$$ is the record for the bus stop $$$i$$$. The bus stops are numbered from $$$1$$$ to $$$n$$$ in chronological order.Determine the number of possible ways how many people could be in the bus before the first bus stop, if the bus has a capacity equals to $$$w$$$ (that is, at any time in the bus there should be from $$$0$$$ to $$$w$$$ passengers inclusive).",['math']41"One day Vitaly was going home late at night and wondering: how many people aren't sleeping at that moment? To estimate, Vitaly decided to look which windows are lit in the house he was passing by at that moment.Vitaly sees a building of n floors and 2·m windows on each floor. On each floor there are m flats numbered from 1 to m, and two consecutive windows correspond to each flat. If we number the windows from 1 to 2·m from left to right, then the j-th flat of the i-th floor has windows 2·j - 1 and 2·j in the corresponding row of windows (as usual, floors are enumerated from the bottom). Vitaly thinks that people in the flat aren't sleeping at that moment if at least one of the windows corresponding to this flat has lights on.Given the information about the windows of the given house, your task is to calculate the number of flats where, according to Vitaly, people aren't sleeping.",[]42"In some social network, there are $$$n$$$ users communicating with each other in $$$m$$$ groups of friends. Let's analyze the process of distributing some news between users.Initially, some user $$$x$$$ receives the news from some source. Then he or she sends the news to his or her friends (two users are friends if there is at least one group such that both of them belong to this group). Friends continue sending the news to their friends, and so on. The process ends when there is no pair of friends such that one of them knows the news, and another one doesn't know.For each user $$$x$$$ you have to determine what is the number of users that will know the news if initially only user $$$x$$$ starts distributing it. ",['graphs']43"Oleg the bank client checks share prices every day. There are n share prices he is interested in. Today he observed that each second exactly one of these prices decreases by k rubles (note that each second exactly one price changes, but at different seconds different prices can change). Prices can become negative. Oleg found this process interesting, and he asked Igor the financial analyst, what is the minimum time needed for all n prices to become equal, or it is impossible at all? Igor is busy right now, so he asked you to help Oleg. Can you answer this question?",['math']44"Recently Luba bought a monitor. Monitor is a rectangular matrix of size n × m. But then she started to notice that some pixels cease to work properly. Luba thinks that the monitor will become broken the first moment when it contains a square k × k consisting entirely of broken pixels. She knows that q pixels are already broken, and for each of them she knows the moment when it stopped working. Help Luba to determine when the monitor became broken (or tell that it's still not broken even after all q pixels stopped working).",[]45"You have $$$n$$$ gifts and you want to give all of them to children. Of course, you don't want to offend anyone, so all gifts should be equal between each other. The $$$i$$$-th gift consists of $$$a_i$$$ candies and $$$b_i$$$ oranges.During one move, you can choose some gift $$$1 \le i \le n$$$ and do one of the following operations:  eat exactly one candy from this gift (decrease $$$a_i$$$ by one);  eat exactly one orange from this gift (decrease $$$b_i$$$ by one);  eat exactly one candy and exactly one orange from this gift (decrease both $$$a_i$$$ and $$$b_i$$$ by one). Of course, you can not eat a candy or orange if it's not present in the gift (so neither $$$a_i$$$ nor $$$b_i$$$ can become less than zero).As said above, all gifts should be equal. This means that after some sequence of moves the following two conditions should be satisfied: $$$a_1 = a_2 = \dots = a_n$$$ and $$$b_1 = b_2 = \dots = b_n$$$ (and $$$a_i$$$ equals $$$b_i$$$ is not necessary).Your task is to find the minimum number of moves required to equalize all the given gifts.You have to answer $$$t$$$ independent test cases.",[]46"You've been in love with Coronavirus-chan for a long time, but you didn't know where she lived until now. And just now you found out that she lives in a faraway place called Naha. You immediately decided to take a vacation and visit Coronavirus-chan. Your vacation lasts exactly $$$x$$$ days and that's the exact number of days you will spend visiting your friend. You will spend exactly $$$x$$$ consecutive (successive) days visiting Coronavirus-chan.They use a very unusual calendar in Naha: there are $$$n$$$ months in a year, $$$i$$$-th month lasts exactly $$$d_i$$$ days. Days in the $$$i$$$-th month are numbered from $$$1$$$ to $$$d_i$$$. There are no leap years in Naha.The mood of Coronavirus-chan (and, accordingly, her desire to hug you) depends on the number of the day in a month. In particular, you get $$$j$$$ hugs if you visit Coronavirus-chan on the $$$j$$$-th day of the month.You know about this feature of your friend and want to plan your trip to get as many hugs as possible (and then maybe you can win the heart of Coronavirus-chan). Please note that your trip should not necessarily begin and end in the same year.",[]47"A wise man told Kerem ""Different is good"" once, so Kerem wants all things in his life to be different. Kerem recently got a string s consisting of lowercase English letters. Since Kerem likes it when things are different, he wants all substrings of his string s to be distinct. Substring is a string formed by some number of consecutive characters of the string. For example, string ""aba"" has substrings """" (empty substring), ""a"", ""b"", ""a"", ""ab"", ""ba"", ""aba"".If string s has at least two equal substrings then Kerem will change characters at some positions to some other lowercase English letters. Changing characters is a very tiring job, so Kerem want to perform as few changes as possible.Your task is to find the minimum number of changes needed to make all the substrings of the given string distinct, or determine that it is impossible.",['strings']48"Winters are just damn freezing cold in Nvodsk! That's why a group of n friends prefers to take a taxi, order a pizza and call girls. The phone numbers in the city consist of three pairs of digits (for example, 12-34-56). Each friend has a phonebook of size si (that's the number of phone numbers). We know that taxi numbers consist of six identical digits (for example, 22-22-22), the numbers of pizza deliveries should necessarily be decreasing sequences of six different digits (for example, 98-73-21), all other numbers are the girls' numbers.You are given your friends' phone books. Calculate which friend is best to go to when you are interested in each of those things (who has maximal number of phone numbers of each type). If the phone book of one person contains some number two times, you should count it twice. That is, each number should be taken into consideration the number of times it occurs in the phone book.",['strings']49"You are given an array $$$a_1, a_2, \dots , a_n$$$. Array is good if for each pair of indexes $$$i < j$$$ the condition $$$j - a_j \ne i - a_i$$$ holds. Can you shuffle this array so that it becomes good? To shuffle an array means to reorder its elements arbitrarily (leaving the initial order is also an option).For example, if $$$a = [1, 1, 3, 5]$$$, then shuffled arrays $$$[1, 3, 5, 1]$$$, $$$[3, 5, 1, 1]$$$ and $$$[5, 3, 1, 1]$$$ are good, but shuffled arrays $$$[3, 1, 5, 1]$$$, $$$[1, 1, 3, 5]$$$ and $$$[1, 1, 5, 3]$$$ aren't.It's guaranteed that it's always possible to shuffle an array to meet this condition.",[]50"Magnus decided to play a classic chess game. Though what he saw in his locker shocked him! His favourite chessboard got broken into 4 pieces, each of size n by n, n is always odd. And what's even worse, some squares were of wrong color. j-th square of the i-th row of k-th piece of the board has color ak, i, j; 1 being black and 0 being white. Now Magnus wants to change color of some squares in such a way that he recolors minimum number of squares and obtained pieces form a valid chessboard. Every square has its color different to each of the neightbouring by side squares in a valid board. Its size should be 2n by 2n. You are allowed to move pieces but not allowed to rotate or flip them.",[]51"One day Squidward, Spongebob and Patrick decided to go to the beach. Unfortunately, the weather was bad, so the friends were unable to ride waves. However, they decided to spent their time building sand castles.At the end of the day there were n castles built by friends. Castles are numbered from 1 to n, and the height of the i-th castle is equal to hi. When friends were about to leave, Squidward noticed, that castles are not ordered by their height, and this looks ugly. Now friends are going to reorder the castles in a way to obtain that condition hi ≤ hi + 1 holds for all i from 1 to n - 1.Squidward suggested the following process of sorting castles:   Castles are split into blocks — groups of consecutive castles. Therefore the block from i to j will include castles i, i + 1, ..., j. A block may consist of a single castle.  The partitioning is chosen in such a way that every castle is a part of exactly one block.  Each block is sorted independently from other blocks, that is the sequence hi, hi + 1, ..., hj becomes sorted.  The partitioning should satisfy the condition that after each block is sorted, the sequence hi becomes sorted too. This may always be achieved by saying that the whole sequence is a single block. Even Patrick understands that increasing the number of blocks in partitioning will ease the sorting process. Now friends ask you to count the maximum possible number of blocks in a partitioning that satisfies all the above requirements.",[]52"There is a conveyor with $$$120$$$ rows and $$$120$$$ columns. Each row and column is numbered from $$$0$$$ to $$$119$$$, and the cell in $$$i$$$-th row and $$$j$$$-th column is denoted as $$$(i, j)$$$. The top leftmost cell is $$$(0, 0)$$$. Each cell has a belt, and all belts are initially facing to the right.Initially, a slime ball is on the belt of $$$(0, 0)$$$, and other belts are empty. Every second, the state of the conveyor changes as follows:   All slime balls on the conveyor move one cell in the direction of the belt at the same time. If there is no cell in the moved position, the slime gets out of the conveyor, and if two slime balls move to the same cell, they merge into one.  All belts with slime ball in the previous second change direction at the same time: belts facing to the right become facing to the down, and vice versa.  A new slime ball is placed on cell $$$(0, 0)$$$. There are $$$q$$$ queries, each being three integers $$$t$$$, $$$x$$$, and $$$y$$$. You have to find out if there is a slime at the cell $$$(x, y)$$$ after $$$t$$$ seconds from the start. Can you do it?",['math']53" — Hey folks, how do you like this problem?— That'll do it. BThero is a powerful magician. He has got $$$n$$$ piles of candies, the $$$i$$$-th pile initially contains $$$a_i$$$ candies. BThero can cast a copy-paste spell as follows:   He chooses two piles $$$(i, j)$$$ such that $$$1 \le i, j \le n$$$ and $$$i \ne j$$$.  All candies from pile $$$i$$$ are copied into pile $$$j$$$. Formally, the operation $$$a_j := a_j + a_i$$$ is performed. BThero can cast this spell any number of times he wants to — but unfortunately, if some pile contains strictly more than $$$k$$$ candies, he loses his magic power. What is the maximum number of times BThero can cast the spell without losing his power?",['math']54"...Once upon a time a man came to the sea. The sea was stormy and dark. The man started to call for the little mermaid to appear but alas, he only woke up Cthulhu...Whereas on the other end of the world Pentagon is actively collecting information trying to predict the monster's behavior and preparing the secret super weapon. Due to high seismic activity and poor weather conditions the satellites haven't yet been able to make clear shots of the monster. The analysis of the first shot resulted in an undirected graph with n vertices and m edges. Now the world's best minds are about to determine whether this graph can be regarded as Cthulhu or not.To add simplicity, let's suppose that Cthulhu looks from the space like some spherical body with tentacles attached to it. Formally, we shall regard as Cthulhu such an undirected graph that can be represented as a set of three or more rooted trees, whose roots are connected by a simple cycle.It is guaranteed that the graph contains no multiple edges and self-loops.  ",['graphs']55"Recently, Tokitsukaze found an interesting game. Tokitsukaze had $$$n$$$ items at the beginning of this game. However, she thought there were too many items, so now she wants to discard $$$m$$$ ($$$1 \le m \le n$$$) special items of them.These $$$n$$$ items are marked with indices from $$$1$$$ to $$$n$$$. In the beginning, the item with index $$$i$$$ is placed on the $$$i$$$-th position. Items are divided into several pages orderly, such that each page contains exactly $$$k$$$ positions and the last positions on the last page may be left empty.Tokitsukaze would do the following operation: focus on the first special page that contains at least one special item, and at one time, Tokitsukaze would discard all special items on this page. After an item is discarded or moved, its old position would be empty, and then the item below it, if exists, would move up to this empty position. The movement may bring many items forward and even into previous pages, so Tokitsukaze would keep waiting until all the items stop moving, and then do the operation (i.e. check the special page and discard the special items) repeatedly until there is no item need to be discarded.    Consider the first example from the statement: $$$n=10$$$, $$$m=4$$$, $$$k=5$$$, $$$p=[3, 5, 7, 10]$$$. The are two pages. Initially, the first page is special (since it is the first page containing a special item). So Tokitsukaze discards the special items with indices $$$3$$$ and $$$5$$$. After, the first page remains to be special. It contains $$$[1, 2, 4, 6, 7]$$$, Tokitsukaze discards the special item with index $$$7$$$. After, the second page is special (since it is the first page containing a special item). It contains $$$[9, 10]$$$, Tokitsukaze discards the special item with index $$$10$$$. Tokitsukaze wants to know the number of operations she would do in total.",[]56"You are given three multisets of pairs of colored sticks:   $$$R$$$ pairs of red sticks, the first pair has length $$$r_1$$$, the second pair has length $$$r_2$$$, $$$\dots$$$, the $$$R$$$-th pair has length $$$r_R$$$;  $$$G$$$ pairs of green sticks, the first pair has length $$$g_1$$$, the second pair has length $$$g_2$$$, $$$\dots$$$, the $$$G$$$-th pair has length $$$g_G$$$;  $$$B$$$ pairs of blue sticks, the first pair has length $$$b_1$$$, the second pair has length $$$b_2$$$, $$$\dots$$$, the $$$B$$$-th pair has length $$$b_B$$$; You are constructing rectangles from these pairs of sticks with the following process:   take a pair of sticks of one color;  take a pair of sticks of another color different from the first one;  add the area of the resulting rectangle to the total area. Thus, you get such rectangles that their opposite sides are the same color and their adjacent sides are not the same color.Each pair of sticks can be used at most once, some pairs can be left unused. You are not allowed to split a pair into independent sticks.What is the maximum area you can achieve?",[]57"Calculate the minimum number of characters you need to change in the string s, so that it contains at least k different letters, or print that it is impossible.String s consists only of lowercase Latin letters, and it is allowed to change characters only to lowercase Latin letters too.",['strings']58"Ashish has a string $$$s$$$ of length $$$n$$$ containing only characters 'a', 'b' and 'c'.He wants to find the length of the smallest substring, which satisfies the following conditions:   Length of the substring is at least $$$2$$$  'a' occurs strictly more times in this substring than 'b'  'a' occurs strictly more times in this substring than 'c'  Ashish is busy planning his next Codeforces round. Help him solve the problem.A string $$$a$$$ is a substring of a string $$$b$$$ if $$$a$$$ can be obtained from $$$b$$$ by deletion of several (possibly, zero or all) characters from the beginning and several (possibly, zero or all) characters from the end.",['strings']59"A permutation of length $$$n$$$ is a sequence of integers from $$$1$$$ to $$$n$$$ of length $$$n$$$ containing each number exactly once. For example, $$$[1]$$$, $$$[4, 3, 5, 1, 2]$$$, $$$[3, 2, 1]$$$ are permutations, and $$$[1, 1]$$$, $$$[0, 1]$$$, $$$[2, 2, 1, 4]$$$ are not.There was a permutation $$$p[1 \dots n]$$$. It was merged with itself. In other words, let's take two instances of $$$p$$$ and insert elements of the second $$$p$$$ into the first maintaining relative order of elements. The result is a sequence of the length $$$2n$$$.For example, if $$$p=[3, 1, 2]$$$ some possible results are: $$$[3, 1, 2, 3, 1, 2]$$$, $$$[3, 3, 1, 1, 2, 2]$$$, $$$[3, 1, 3, 1, 2, 2]$$$. The following sequences are not possible results of a merging: $$$[1, 3, 2, 1, 2, 3$$$], [$$$3, 1, 2, 3, 2, 1]$$$, $$$[3, 3, 1, 2, 2, 1]$$$.For example, if $$$p=[2, 1]$$$ the possible results are: $$$[2, 2, 1, 1]$$$, $$$[2, 1, 2, 1]$$$. The following sequences are not possible results of a merging: $$$[1, 1, 2, 2$$$], [$$$2, 1, 1, 2]$$$, $$$[1, 2, 2, 1]$$$.Your task is to restore the permutation $$$p$$$ by the given resulting sequence $$$a$$$. It is guaranteed that the answer exists and is unique.You have to answer $$$t$$$ independent test cases.",[]60"Given an array $$$a$$$ of $$$n$$$ elements, print any value that appears at least three times or print -1 if there is no such value.",[]61"Let $$$F_k$$$ denote the $$$k$$$-th term of Fibonacci sequence, defined as below: $$$F_0 = F_1 = 1$$$ for any integer $$$n \geq 0$$$, $$$F_{n+2} = F_{n+1} + F_n$$$You are given a tree with $$$n$$$ vertices. Recall that a tree is a connected undirected graph without cycles.We call a tree a Fib-tree, if its number of vertices equals $$$F_k$$$ for some $$$k$$$, and at least one of the following conditions holds: The tree consists of only $$$1$$$ vertex; You can divide it into two Fib-trees by removing some edge of the tree. Determine whether the given tree is a Fib-tree or not.","['number theory', 'trees']"62"Sensation, sensation in the two-dimensional kingdom! The police have caught a highly dangerous outlaw, member of the notorious ""Pihters"" gang. The law department states that the outlaw was driving from the gang's headquarters in his car when he crashed into an ice cream stall. The stall, the car, and the headquarters each occupies exactly one point on the two-dimensional kingdom.The outlaw's car was equipped with a GPS transmitter. The transmitter showed that the car made exactly n movements on its way from the headquarters to the stall. A movement can move the car from point (x, y) to one of these four points: to point (x - 1, y) which we will mark by letter ""L"", to point (x + 1, y) — ""R"", to point (x, y - 1) — ""D"", to point (x, y + 1) — ""U"".The GPS transmitter is very inaccurate and it doesn't preserve the exact sequence of the car's movements. Instead, it keeps records of the car's possible movements. Each record is a string of one of these types: ""UL"", ""UR"", ""DL"", ""DR"" or ""ULDR"". Each such string means that the car made a single movement corresponding to one of the characters of the string. For example, string ""UL"" means that the car moved either ""U"", or ""L"".You've received the journal with the outlaw's possible movements from the headquarters to the stall. The journal records are given in a chronological order. Given that the ice-cream stall is located at point (0, 0), your task is to print the number of different points that can contain the gang headquarters (that is, the number of different possible locations of the car's origin).",['math']63"Devu being a small kid, likes to play a lot, but he only likes to play with arrays. While playing he came up with an interesting question which he could not solve, can you please solve it for him?Given an array consisting of distinct integers. Is it possible to partition the whole array into k disjoint non-empty parts such that p of the parts have even sum (each of them must have even sum) and remaining k - p have odd sum? (note that parts need not to be continuous).If it is possible to partition the array, also give any possible way of valid partitioning.",['number theory']64"For given n, l and r find the number of distinct geometrical progression, each of which contains n distinct integers not less than l and not greater than r. In other words, for each progression the following must hold: l ≤ ai ≤ r and ai ≠ aj , where a1, a2, ..., an is the geometrical progression, 1 ≤ i, j ≤ n and i ≠ j.Geometrical progression is a sequence of numbers a1, a2, ..., an where each term after first is found by multiplying the previous one by a fixed non-zero number d called the common ratio. Note that in our task d may be non-integer. For example in progression 4, 6, 9, common ratio is .Two progressions a1, a2, ..., an and b1, b2, ..., bn are considered different, if there is such i (1 ≤ i ≤ n) that ai ≠ bi.","['math', 'number theory']"65"You are given a chessboard consisting of $$$n$$$ rows and $$$n$$$ columns. Rows are numbered from bottom to top from $$$1$$$ to $$$n$$$. Columns are numbered from left to right from $$$1$$$ to $$$n$$$. The cell at the intersection of the $$$x$$$-th column and the $$$y$$$-th row is denoted as $$$(x, y)$$$. Furthermore, the $$$k$$$-th column is a special column. Initially, the board is empty. There are $$$m$$$ changes to the board. During the $$$i$$$-th change one pawn is added or removed from the board. The current board is good if we can move all pawns to the special column by the followings rules:  Pawn in the cell $$$(x, y)$$$ can be moved to the cell $$$(x, y + 1)$$$, $$$(x - 1, y + 1)$$$ or $$$(x + 1, y + 1)$$$;  You can make as many such moves as you like;  Pawns can not be moved outside the chessboard;  Each cell can not contain more than one pawn. The current board may not always be good. To fix it, you can add new rows to the board. New rows are added at the top, i. e. they will have numbers $$$n+1, n+2, n+3, \dots$$$.After each of $$$m$$$ changes, print one integer — the minimum number of rows which you have to add to make the board good.",[]66"Andrew skipped lessons on the subject 'Algorithms and Data Structures' for the entire term. When he came to the final test, the teacher decided to give him a difficult task as a punishment.The teacher gave Andrew an array of n numbers a1, ..., an. After that he asked Andrew for each k from 1 to n - 1 to build a k-ary heap on the array and count the number of elements for which the property of the minimum-rooted heap is violated, i.e. the value of an element is less than the value of its parent.Andrew looked up on the Wikipedia that a k-ary heap is a rooted tree with vertices in elements of the array. If the elements of the array are indexed from 1 to n, then the children of element v are elements with indices k(v - 1) + 2, ..., kv + 1 (if some of these elements lie outside the borders of the array, the corresponding children are absent). In any k-ary heap every element except for the first one has exactly one parent; for the element 1 the parent is absent (this element is the root of the heap). Denote p(v) as the number of the parent of the element with the number v. Let's say that for a non-root element v the property of the heap is violated if av < ap(v).Help Andrew cope with the task!",['math']67"This is a hard version of the problem. The actual problems are different, but the easy version is almost a subtask of the hard version. Note that the constraints and the output format are different.You are given a string $$$s$$$ consisting of $$$n$$$ lowercase Latin letters.You have to color all its characters the minimum number of colors (each character to exactly one color, the same letters can be colored the same or different colors, i.e. you can choose exactly one color for each index in $$$s$$$).After coloring, you can swap any two neighboring characters of the string that are colored different colors. You can perform such an operation arbitrary (possibly, zero) number of times.The goal is to make the string sorted, i.e. all characters should be in alphabetical order.Your task is to find the minimum number of colors which you have to color the given string in so that after coloring it can become sorted by some sequence of swaps. Note that you have to restore only coloring, not the sequence of swaps.",[]68"Bob is a farmer. He has a large pasture with many sheep. Recently, he has lost some of them due to wolf attacks. He thus decided to place some shepherd dogs in such a way that all his sheep are protected.The pasture is a rectangle consisting of R × C cells. Each cell is either empty, contains a sheep, a wolf or a dog. Sheep and dogs always stay in place, but wolves can roam freely around the pasture, by repeatedly moving to the left, right, up or down to a neighboring cell. When a wolf enters a cell with a sheep, it consumes it. However, no wolf can enter a cell with a dog.Initially there are no dogs. Place dogs onto the pasture in such a way that no wolf can reach any sheep, or determine that it is impossible. Note that since you have many dogs, you do not need to minimize their number. ",['graphs']69"A non-empty string is called palindrome, if it reads the same from the left to the right and from the right to the left. For example, ""abcba"", ""a"", and ""abba"" are palindromes, while ""abab"" and ""xy"" are not.A string is called a substring of another string, if it can be obtained from that string by dropping some (possibly zero) number of characters from the beginning and from the end of it. For example, ""abc"", ""ab"", and ""c"" are substrings of the string ""abc"", while ""ac"" and ""d"" are not.Let's define a palindromic count of the string as the number of its substrings that are palindromes. For example, the palindromic count of the string ""aaa"" is $$$6$$$ because all its substrings are palindromes, and the palindromic count of the string ""abc"" is $$$3$$$ because only its substrings of length $$$1$$$ are palindromes.You are given a string $$$s$$$. You can arbitrarily rearrange its characters. You goal is to obtain a string with the maximum possible value of palindromic count.",[]70"Polycarp has found a table having an infinite number of rows and columns. The rows are numbered from $$$1$$$, starting from the topmost one. The columns are numbered from $$$1$$$, starting from the leftmost one.Initially, the table hasn't been filled and Polycarp wants to fix it. He writes integers from $$$1$$$ and so on to the table as follows.  The figure shows the placement of the numbers from $$$1$$$ to $$$10$$$. The following actions are denoted by the arrows. The leftmost topmost cell of the table is filled with the number $$$1$$$. Then he writes in the table all positive integers beginning from $$$2$$$ sequentially using the following algorithm.First, Polycarp selects the leftmost non-filled cell in the first row and fills it. Then, while the left neighbor of the last filled cell is filled, he goes down and fills the next cell. So he goes down until the last filled cell has a non-filled neighbor to the left (look at the vertical arrow going down in the figure above).After that, he fills the cells from the right to the left until he stops at the first column (look at the horizontal row in the figure above). Then Polycarp selects the leftmost non-filled cell in the first row, goes down, and so on.A friend of Polycarp has a favorite number $$$k$$$. He wants to know which cell will contain the number. Help him to find the indices of the row and the column, such that the intersection of the row and the column is the cell containing the number $$$k$$$.",['math']71"Theofanis started playing the new online game called ""Among them"". However, he always plays with Cypriot players, and they all have the same name: ""Andreas"" (the most common name in Cyprus).In each game, Theofanis plays with $$$n$$$ other players. Since they all have the same name, they are numbered from $$$1$$$ to $$$n$$$.The players write $$$m$$$ comments in the chat. A comment has the structure of ""$$$i$$$ $$$j$$$ $$$c$$$"" where $$$i$$$ and $$$j$$$ are two distinct integers and $$$c$$$ is a string ($$$1 \le i, j \le n$$$; $$$i \neq j$$$; $$$c$$$ is either imposter or crewmate). The comment means that player $$$i$$$ said that player $$$j$$$ has the role $$$c$$$.An imposter always lies, and a crewmate always tells the truth. Help Theofanis find the maximum possible number of imposters among all the other Cypriot players, or determine that the comments contradict each other (see the notes for further explanation).Note that each player has exactly one role: either imposter or crewmate.",['graphs']72"You are given two lists of segments $$$[al_1, ar_1], [al_2, ar_2], \dots, [al_n, ar_n]$$$ and $$$[bl_1, br_1], [bl_2, br_2], \dots, [bl_n, br_n]$$$.Initially, all segments $$$[al_i, ar_i]$$$ are equal to $$$[l_1, r_1]$$$ and all segments $$$[bl_i, br_i]$$$ are equal to $$$[l_2, r_2]$$$.In one step, you can choose one segment (either from the first or from the second list) and extend it by $$$1$$$. In other words, suppose you've chosen segment $$$[x, y]$$$ then you can transform it either into $$$[x - 1, y]$$$ or into $$$[x, y + 1]$$$.Let's define a total intersection $$$I$$$ as the sum of lengths of intersections of the corresponding pairs of segments, i.e. $$$\sum\limits_{i=1}^{n}{\text{intersection_length}([al_i, ar_i], [bl_i, br_i])}$$$. Empty intersection has length $$$0$$$ and length of a segment $$$[x, y]$$$ is equal to $$$y - x$$$.What is the minimum number of steps you need to make $$$I$$$ greater or equal to $$$k$$$?",['math']73"There is a fence in front of Polycarpus's home. The fence consists of n planks of the same width which go one after another from left to right. The height of the i-th plank is hi meters, distinct planks can have distinct heights.    Fence for n = 7 and h = [1, 2, 6, 1, 1, 7, 1] Polycarpus has bought a posh piano and is thinking about how to get it into the house. In order to carry out his plan, he needs to take exactly k consecutive planks from the fence. Higher planks are harder to tear off the fence, so Polycarpus wants to find such k consecutive planks that the sum of their heights is minimal possible.Write the program that finds the indexes of k consecutive planks with minimal total height. Pay attention, the fence is not around Polycarpus's home, it is in front of home (in other words, the fence isn't cyclic).",[]74"You are playing a computer card game called Splay the Sire. Currently you are struggling to defeat the final boss of the game.The boss battle consists of $$$n$$$ turns. During each turn, you will get several cards. Each card has two parameters: its cost $$$c_i$$$ and damage $$$d_i$$$. You may play some of your cards during each turn in some sequence (you choose the cards and the exact order they are played), as long as the total cost of the cards you play during the turn does not exceed $$$3$$$. After playing some (possibly zero) cards, you end your turn, and all cards you didn't play are discarded. Note that you can use each card at most once.Your character has also found an artifact that boosts the damage of some of your actions: every $$$10$$$-th card you play deals double damage.What is the maximum possible damage you can deal during $$$n$$$ turns?",[]75"Orac is studying number theory, and he is interested in the properties of divisors.For two positive integers $$$a$$$ and $$$b$$$, $$$a$$$ is a divisor of $$$b$$$ if and only if there exists an integer $$$c$$$, such that $$$a\cdot c=b$$$.For $$$n \ge 2$$$, we will denote as $$$f(n)$$$ the smallest positive divisor of $$$n$$$, except $$$1$$$.For example, $$$f(7)=7,f(10)=2,f(35)=5$$$.For the fixed integer $$$n$$$, Orac decided to add $$$f(n)$$$ to $$$n$$$. For example, if he had an integer $$$n=5$$$, the new value of $$$n$$$ will be equal to $$$10$$$. And if he had an integer $$$n=6$$$, $$$n$$$ will be changed to $$$8$$$.Orac loved it so much, so he decided to repeat this operation several times.Now, for two positive integers $$$n$$$ and $$$k$$$, Orac asked you to add $$$f(n)$$$ to $$$n$$$ exactly $$$k$$$ times (note that $$$n$$$ will change after each operation, so $$$f(n)$$$ may change too) and tell him the final value of $$$n$$$.For example, if Orac gives you $$$n=5$$$ and $$$k=2$$$, at first you should add $$$f(5)=5$$$ to $$$n=5$$$, so your new value of $$$n$$$ will be equal to $$$n=10$$$, after that, you should add $$$f(10)=2$$$ to $$$10$$$, so your new (and the final!) value of $$$n$$$ will be equal to $$$12$$$.Orac may ask you these queries many times.",['math']76You are given a string s consisting of lowercase Latin letters. Character c is called k-dominant iff each substring of s with length at least k contains this character c.You have to find minimum k such that there exists at least one k-dominant character.,[]77"Dima is a good person. In fact, he's great. But all good things come to an end...Seryozha is going to kick Dima just few times.. For this reason he divides the room into unit squares. Now the room is a rectangle n × m consisting of unit squares.For the beginning, Seryozha put Dima in a center of some square. Then he started to kick Dima (it is known, that he kicks Dima at least once). Each time when Dima is kicked he flyes up and moves into one of four directions (up, left, right, down). On each move Dima passes k (k > 1) unit of the length in the corresponding direction. Seryozha is really kind, so he kicks Dima in such way that Dima never meets the walls (in other words, Dima never leave the room's space). Seryozha is also dynamic character so Dima never flies above the same segment, connecting a pair of adjacent squares, twice.Seryozha kicks Dima for a long time, but Dima is not vindictive — Dima writes. Dima marked all squares in which he was staying or above which he was flying. Thanks to kicks, Dima does not remember the k value, so he asks you to find all possible values which matches to the Dima's records.",['graphs']78"We just discovered a new data structure in our research group: a suffix three!It's very useful for natural language processing. Given three languages and three suffixes, a suffix three can determine which language a sentence is written in.It's super simple, 100% accurate, and doesn't involve advanced machine learning algorithms.Let us tell you how it works.  If a sentence ends with ""po"" the language is Filipino.  If a sentence ends with ""desu"" or ""masu"" the language is Japanese.  If a sentence ends with ""mnida"" the language is Korean. Given this, we need you to implement a suffix three that can differentiate Filipino, Japanese, and Korean.Oh, did I say three suffixes? I meant four.",[]79"After rejecting $$$10^{100}$$$ data structure problems, Errorgorn is very angry at Anton and decided to kill him.Anton's DNA can be represented as a string $$$a$$$ which only contains the characters ""ANTON"" (there are only $$$4$$$ distinct characters). Errorgorn can change Anton's DNA into string $$$b$$$ which must be a permutation of $$$a$$$. However, Anton's body can defend against this attack. In $$$1$$$ second, his body can swap $$$2$$$ adjacent characters of his DNA to transform it back to $$$a$$$. Anton's body is smart and will use the minimum number of moves.To maximize the chance of Anton dying, Errorgorn wants to change Anton's DNA the string that maximizes the time for Anton's body to revert his DNA. But since Errorgorn is busy making more data structure problems, he needs your help to find the best string $$$B$$$. Can you help him?","['math', 'strings']"80"Vasya has recently found out what a digital root of a number is and he decided to share his knowledge with you.Let's assume that S(n) is the sum of digits of number n, for example, S(4098) = 4 + 0 + 9 + 8 = 21. Then the digital root of number n equals to:   dr(n) = S(n), if S(n) < 10;  dr(n) = dr( S(n) ), if S(n) ≥ 10. For example, dr(4098)  =  dr(21)  =  3.Vasya is afraid of large numbers, so the numbers he works with are at most 101000. For all such numbers, he has proved that dr(n)  =  S( S( S( S(n) ) ) ) (n ≤ 101000).Now Vasya wants to quickly find numbers with the given digital root. The problem is, he hasn't learned how to do that and he asked you to help him. You task is, given numbers k and d, find the number consisting of exactly k digits (the leading zeroes are not allowed), with digital root equal to d, or else state that such number does not exist.",[]81"You are given an integer $$$n$$$. In one move, you can either multiply $$$n$$$ by two or divide $$$n$$$ by $$$6$$$ (if it is divisible by $$$6$$$ without the remainder).Your task is to find the minimum number of moves needed to obtain $$$1$$$ from $$$n$$$ or determine if it's impossible to do that.You have to answer $$$t$$$ independent test cases.",['math']82"You are given a sequence of $$$n$$$ integers $$$a_1, a_2, \ldots, a_n$$$.You have to construct two sequences of integers $$$b$$$ and $$$c$$$ with length $$$n$$$ that satisfy:  for every $$$i$$$ ($$$1\leq i\leq n$$$) $$$b_i+c_i=a_i$$$  $$$b$$$ is non-decreasing, which means that for every $$$1<i\leq n$$$, $$$b_i\geq b_{i-1}$$$ must hold  $$$c$$$ is non-increasing, which means that for every $$$1<i\leq n$$$, $$$c_i\leq c_{i-1}$$$ must hold You have to minimize $$$\max(b_i,c_i)$$$. In other words, you have to minimize the maximum number in sequences $$$b$$$ and $$$c$$$.Also there will be $$$q$$$ changes, the $$$i$$$-th change is described by three integers $$$l,r,x$$$. You should add $$$x$$$ to $$$a_l,a_{l+1}, \ldots, a_r$$$. You have to find the minimum possible value of $$$\max(b_i,c_i)$$$ for the initial sequence and for sequence after each change.",['math']83"Meanwhile, the kingdom of K is getting ready for the marriage of the King's daughter. However, in order not to lose face in front of the relatives, the King should first finish reforms in his kingdom. As the King can not wait for his daughter's marriage, reforms must be finished as soon as possible.The kingdom currently consists of n cities. Cities are connected by n - 1 bidirectional road, such that one can get from any city to any other city. As the King had to save a lot, there is only one path between any two cities.What is the point of the reform? The key ministries of the state should be relocated to distinct cities (we call such cities important). However, due to the fact that there is a high risk of an attack by barbarians it must be done carefully. The King has made several plans, each of which is described by a set of important cities, and now wonders what is the best plan.Barbarians can capture some of the cities that are not important (the important ones will have enough protection for sure), after that the captured city becomes impassable. In particular, an interesting feature of the plan is the minimum number of cities that the barbarians need to capture in order to make all the important cities isolated, that is, from all important cities it would be impossible to reach any other important city.Help the King to calculate this characteristic for each of his plan.","['graphs', 'trees']"84"The only difference between the easy and hard versions is the constraints on the number of queries.This is an interactive problem.Ridbit has a hidden array $$$a$$$ of $$$n$$$ integers which he wants Ashish to guess. Note that $$$n$$$ is a power of two. Ashish is allowed to ask three different types of queries. They are of the form   AND $$$i$$$ $$$j$$$: ask for the bitwise AND of elements $$$a_i$$$ and $$$a_j$$$ $$$(1 \leq i, j \le n$$$, $$$i \neq j)$$$  OR $$$i$$$ $$$j$$$: ask for the bitwise OR of elements $$$a_i$$$ and $$$a_j$$$ $$$(1 \leq i, j \le n$$$, $$$i \neq j)$$$  XOR $$$i$$$ $$$j$$$: ask for the bitwise XOR of elements $$$a_i$$$ and $$$a_j$$$ $$$(1 \leq i, j \le n$$$, $$$i \neq j)$$$ Can you help Ashish guess the elements of the array?In this version, each element takes a value in the range $$$[0, n-1]$$$ (inclusive) and Ashish can ask no more than $$$n+1$$$ queries.",['math']85"Pikachu had an array with him. He wrote down all the non-empty subsequences of the array on paper. Note that an array of size n has 2n - 1 non-empty subsequences in it. Pikachu being mischievous as he always is, removed all the subsequences in which Maximum_element_of_the_subsequence  -  Minimum_element_of_subsequence  ≥ dPikachu was finally left with X subsequences. However, he lost the initial array he had, and now is in serious trouble. He still remembers the numbers X and d. He now wants you to construct any such array which will satisfy the above conditions. All the numbers in the final array should be positive integers less than 1018. Note the number of elements in the output array should not be more than 104. If no answer is possible, print  - 1.",[]86"Polycarp was recently given a set of $$$n$$$ (number $$$n$$$ — even) dominoes. Each domino contains two integers from $$$1$$$ to $$$n$$$.Can he divide all the dominoes into two sets so that all the numbers on the dominoes of each set are different? Each domino must go into exactly one of the two sets.For example, if he has $$$4$$$ dominoes: $$$\{1, 4\}$$$, $$$\{1, 3\}$$$, $$$\{3, 2\}$$$ and $$$\{4, 2\}$$$, then Polycarp will be able to divide them into two sets in the required way. The first set can include the first and third dominoes ($$$\{1, 4\}$$$ and $$$\{3, 2\}$$$), and the second set — the second and fourth ones ($$$\{1, 3\}$$$ and $$$\{4, 2\}$$$).",['graphs']87"The Resistance is trying to take control over as many planets of a particular solar system as possible. Princess Heidi is in charge of the fleet, and she must send ships to some planets in order to maximize the number of controlled planets.The Galaxy contains N planets, connected by bidirectional hyperspace tunnels in such a way that there is a unique path between every pair of the planets.A planet is controlled by the Resistance if there is a Resistance ship in its orbit, or if the planet lies on the shortest path between some two planets that have Resistance ships in their orbits.Heidi has not yet made up her mind as to how many ships to use. Therefore, she is asking you to compute, for every K = 1, 2, 3, ..., N, the maximum number of planets that can be controlled with a fleet consisting of K ships.","['graphs', 'trees']"88"You are given a string $$$s$$$ consisting of exactly $$$n$$$ characters, and each character is either '0', '1' or '2'. Such strings are called ternary strings.Your task is to replace minimum number of characters in this string with other characters to obtain a balanced ternary string (balanced ternary string is a ternary string such that the number of characters '0' in this string is equal to the number of characters '1', and the number of characters '1' (and '0' obviously) is equal to the number of characters '2').Among all possible balanced ternary strings you have to obtain the lexicographically (alphabetically) smallest.Note that you can neither remove characters from the string nor add characters to the string. Also note that you can replace the given characters only with characters '0', '1' and '2'.It is guaranteed that the answer exists.",['strings']89"DZY loves planting, and he enjoys solving tree problems.DZY has a weighted tree (connected undirected graph without cycles) containing n nodes (they are numbered from 1 to n). He defines the function g(x, y) (1 ≤ x, y ≤ n) as the longest edge in the shortest path between nodes x and y. Specially g(z, z) = 0 for every z.For every integer sequence p1, p2, ..., pn (1 ≤ pi ≤ n), DZY defines f(p) as . DZY wants to find such a sequence p that f(p) has maximum possible value. But there is one more restriction: the element j can appear in p at most xj times.Please, find the maximum possible f(p) under the described restrictions.",['trees']90"You have a binary string $$$a$$$ of length $$$n$$$ consisting only of digits $$$0$$$ and $$$1$$$. You are given $$$q$$$ queries. In the $$$i$$$-th query, you are given two indices $$$l$$$ and $$$r$$$ such that $$$1 \le l \le r \le n$$$. Let $$$s=a[l,r]$$$. You are allowed to do the following operation on $$$s$$$:  Choose two indices $$$x$$$ and $$$y$$$ such that $$$1 \le x \le y \le |s|$$$. Let $$$t$$$ be the substring $$$t = s[x, y]$$$. Then for all $$$1 \le i \le |t| - 1$$$, the condition $$$t_i \neq t_{i+1}$$$ has to hold. Note that $$$x = y$$$ is always a valid substring.  Delete the substring $$$s[x, y]$$$ from $$$s$$$. For each of the $$$q$$$ queries, find the minimum number of operations needed to make $$$s$$$ an empty string.Note that for a string $$$s$$$, $$$s[l,r]$$$ denotes the subsegment $$$s_l,s_{l+1},\ldots,s_r$$$.",[]91"Monocarp plays ""Rage of Empires II: Definitive Edition"" — a strategic computer game. Right now he's planning to attack his opponent in the game, but Monocarp's forces cannot enter the opponent's territory since the opponent has built a wall.The wall consists of $$$n$$$ sections, aligned in a row. The $$$i$$$-th section initially has durability $$$a_i$$$. If durability of some section becomes $$$0$$$ or less, this section is considered broken.To attack the opponent, Monocarp needs to break at least two sections of the wall (any two sections: possibly adjacent, possibly not). To do this, he plans to use an onager — a special siege weapon. The onager can be used to shoot any section of the wall; the shot deals $$$2$$$ damage to the target section and $$$1$$$ damage to adjacent sections. In other words, if the onager shoots at the section $$$x$$$, then the durability of the section $$$x$$$ decreases by $$$2$$$, and the durability of the sections $$$x - 1$$$ and $$$x + 1$$$ (if they exist) decreases by $$$1$$$ each. Monocarp can shoot at any sections any number of times, he can even shoot at broken sections.Monocarp wants to calculate the minimum number of onager shots needed to break at least two sections. Help him!",['math']92"You are given a sequence $$$a_1, a_2, \dots, a_n$$$, consisting of integers.You can apply the following operation to this sequence: choose some integer $$$x$$$ and move all elements equal to $$$x$$$ either to the beginning, or to the end of $$$a$$$. Note that you have to move all these elements in one direction in one operation.For example, if $$$a = [2, 1, 3, 1, 1, 3, 2]$$$, you can get the following sequences in one operation (for convenience, denote elements equal to $$$x$$$ as $$$x$$$-elements):   $$$[1, 1, 1, 2, 3, 3, 2]$$$ if you move all $$$1$$$-elements to the beginning;  $$$[2, 3, 3, 2, 1, 1, 1]$$$ if you move all $$$1$$$-elements to the end;  $$$[2, 2, 1, 3, 1, 1, 3]$$$ if you move all $$$2$$$-elements to the beginning;  $$$[1, 3, 1, 1, 3, 2, 2]$$$ if you move all $$$2$$$-elements to the end;  $$$[3, 3, 2, 1, 1, 1, 2]$$$ if you move all $$$3$$$-elements to the beginning;  $$$[2, 1, 1, 1, 2, 3, 3]$$$ if you move all $$$3$$$-elements to the end; You have to determine the minimum number of such operations so that the sequence $$$a$$$ becomes sorted in non-descending order. Non-descending order means that for all $$$i$$$ from $$$2$$$ to $$$n$$$, the condition $$$a_{i-1} \le a_i$$$ is satisfied.Note that you have to answer $$$q$$$ independent queries.",[]93"In a building where Polycarp lives there are equal number of flats on each floor. Unfortunately, Polycarp don't remember how many flats are on each floor, but he remembers that the flats are numbered from 1 from lower to upper floors. That is, the first several flats are on the first floor, the next several flats are on the second and so on. Polycarp don't remember the total number of flats in the building, so you can consider the building to be infinitely high (i.e. there are infinitely many floors). Note that the floors are numbered from 1.Polycarp remembers on which floors several flats are located. It is guaranteed that this information is not self-contradictory. It means that there exists a building with equal number of flats on each floor so that the flats from Polycarp's memory have the floors Polycarp remembers.Given this information, is it possible to restore the exact floor for flat n? ",[]94"A new agent called Killjoy invented a virus COVID-2069 that infects accounts on Codeforces. Each account has a rating, described by an integer (it can possibly be negative or very large).Killjoy's account is already infected and has a rating equal to $$$x$$$. Its rating is constant. There are $$$n$$$ accounts except hers, numbered from $$$1$$$ to $$$n$$$. The $$$i$$$-th account's initial rating is $$$a_i$$$. Any infected account (initially the only infected account is Killjoy's) instantly infects any uninfected account if their ratings are equal. This can happen at the beginning (before any rating changes) and after each contest. If an account is infected, it can not be healed.Contests are regularly held on Codeforces. In each contest, any of these $$$n$$$ accounts (including infected ones) can participate. Killjoy can't participate. After each contest ratings are changed this way: each participant's rating is changed by an integer, but the sum of all changes must be equal to zero. New ratings can be any integer.Find out the minimal number of contests needed to infect all accounts. You can choose which accounts will participate in each contest and how the ratings will change.It can be proven that all accounts can be infected in some finite number of contests.",['math']95"Ivan wants to write a letter to his friend. The letter is a string s consisting of lowercase Latin letters.Unfortunately, when Ivan started writing the letter, he realised that it is very long and writing the whole letter may take extremely long time. So he wants to write the compressed version of string s instead of the string itself.The compressed version of string s is a sequence of strings c1, s1, c2, s2, ..., ck, sk, where ci is the decimal representation of number ai (without any leading zeroes) and si is some string consisting of lowercase Latin letters. If Ivan writes string s1 exactly a1 times, then string s2 exactly a2 times, and so on, the result will be string s.The length of a compressed version is |c1| + |s1| + |c2| + |s2|... |ck| + |sk|. Among all compressed versions Ivan wants to choose a version such that its length is minimum possible. Help Ivan to determine minimum possible length.",['strings']96"Limak is a little bear who learns to draw. People usually start with houses, fences and flowers but why would bears do it? Limak lives in the forest and he decides to draw a tree.Recall that tree is a connected graph consisting of n vertices and n - 1 edges.Limak chose a tree with n vertices. He has infinite strip of paper with two parallel rows of dots. Little bear wants to assign vertices of a tree to some n distinct dots on a paper so that edges would intersect only at their endpoints — drawn tree must be planar. Below you can see one of correct drawings for the first sample test.  Is it possible for Limak to draw chosen tree?",[]97"You are given a string $$$s$$$, consisting of lowercase Latin letters. Every letter appears in it no more than twice.Your task is to rearrange the letters in the string in such a way that for each pair of letters that appear exactly twice, the distance between the letters in the pair is the same. You are not allowed to add or remove letters.It can be shown that the answer always exists. If there are multiple answers, print any of them.",[]98"Omkar is playing his favorite pixelated video game, Bed Wars! In Bed Wars, there are $$$n$$$ players arranged in a circle, so that for all $$$j$$$ such that $$$2 \leq j \leq n$$$, player $$$j - 1$$$ is to the left of the player $$$j$$$, and player $$$j$$$ is to the right of player $$$j - 1$$$. Additionally, player $$$n$$$ is to the left of player $$$1$$$, and player $$$1$$$ is to the right of player $$$n$$$.Currently, each player is attacking either the player to their left or the player to their right. This means that each player is currently being attacked by either $$$0$$$, $$$1$$$, or $$$2$$$ other players. A key element of Bed Wars strategy is that if a player is being attacked by exactly $$$1$$$ other player, then they should logically attack that player in response. If instead a player is being attacked by $$$0$$$ or $$$2$$$ other players, then Bed Wars strategy says that the player can logically attack either of the adjacent players.Unfortunately, it might be that some players in this game are not following Bed Wars strategy correctly. Omkar is aware of whom each player is currently attacking, and he can talk to any amount of the $$$n$$$ players in the game to make them instead attack another player  — i. e. if they are currently attacking the player to their left, Omkar can convince them to instead attack the player to their right; if they are currently attacking the player to their right, Omkar can convince them to instead attack the player to their left. Omkar would like all players to be acting logically. Calculate the minimum amount of players that Omkar needs to talk to so that after all players he talked to (if any) have changed which player they are attacking, all players are acting logically according to Bed Wars strategy.",[]99"Furik loves math lessons very much, so he doesn't attend them, unlike Rubik. But now Furik wants to get a good mark for math. For that Ms. Ivanova, his math teacher, gave him a new task. Furik solved the task immediately. Can you?You are given a set of digits, your task is to find the maximum integer that you can make from these digits. The made number must be divisible by 2, 3, 5 without a residue. It is permitted to use not all digits from the set, it is forbidden to use leading zeroes.Each digit is allowed to occur in the number the same number of times it occurs in the set.",['math']100"After a successful year of milk production, Farmer John is rewarding his cows with their favorite treat: tasty grass!On the field, there is a row of $$$n$$$ units of grass, each with a sweetness $$$s_i$$$. Farmer John has $$$m$$$ cows, each with a favorite sweetness $$$f_i$$$ and a hunger value $$$h_i$$$. He would like to pick two disjoint subsets of cows to line up on the left and right side of the grass row. There is no restriction on how many cows must be on either side. The cows will be treated in the following manner:   The cows from the left and right side will take turns feeding in an order decided by Farmer John.  When a cow feeds, it walks towards the other end without changing direction and eats grass of its favorite sweetness until it eats $$$h_i$$$ units.  The moment a cow eats $$$h_i$$$ units, it will fall asleep there, preventing further cows from passing it from both directions.  If it encounters another sleeping cow or reaches the end of the grass row, it will get upset. Farmer John absolutely does not want any cows to get upset. Note that grass does not grow back. Also, to prevent cows from getting upset, not every cow has to feed since FJ can choose a subset of them. Surprisingly, FJ has determined that sleeping cows are the most satisfied. If FJ orders optimally, what is the maximum number of sleeping cows that can result, and how many ways can FJ choose the subset of cows on the left and right side to achieve that maximum number of sleeping cows (modulo $$$10^9+7$$$)? The order in which FJ sends the cows does not matter as long as no cows get upset. ",['math']101"One day Polycarp decided to rewatch his absolute favourite episode of well-known TV series ""Tufurama"". He was pretty surprised when he got results only for season 7 episode 3 with his search query of ""Watch Tufurama season 3 episode 7 online full hd free"". This got Polycarp confused — what if he decides to rewatch the entire series someday and won't be able to find the right episodes to watch? Polycarp now wants to count the number of times he will be forced to search for an episode using some different method.TV series have n seasons (numbered 1 through n), the i-th season has ai episodes (numbered 1 through ai). Polycarp thinks that if for some pair of integers x and y (x < y) exist both season x episode y and season y episode x then one of these search queries will include the wrong results. Help Polycarp to calculate the number of such pairs!",[]102"Due to the increase in the number of students of Berland State University it was decided to equip a new computer room. You were given the task of buying mouses, and you have to spend as little as possible. After all, the country is in crisis!The computers bought for the room were different. Some of them had only USB ports, some — only PS/2 ports, and some had both options.You have found a price list of a certain computer shop. In it, for m mouses it is specified the cost and the type of the port that is required to plug the mouse in (USB or PS/2). Each mouse from the list can be bought at most once.You want to buy some set of mouses from the given price list in such a way so that you maximize the number of computers equipped with mouses (it is not guaranteed that you will be able to equip all of the computers), and in case of equality of this value you want to minimize the total cost of mouses you will buy.",[]103"Recall that the bracket sequence is considered regular if it is possible to insert symbols '+' and '1' into it so that the result is a correct arithmetic expression. For example, a sequence ""(()())"" is regular, because we can get correct arithmetic expression insering symbols '+' and '1': ""((1+1)+(1+1))"". Also the following sequences are regular: ""()()()"", ""(())"" and ""()"". The following sequences are not regular bracket sequences: "")("", ""(()"" and ""())(()"".In this problem you are given two integers n and k. Your task is to construct a regular bracket sequence consisting of round brackets with length 2·n with total sum of nesting of all opening brackets equals to exactly k. The nesting of a single opening bracket equals to the number of pairs of brackets in which current opening bracket is embedded.For example, in the sequence ""()(())"" the nesting of first opening bracket equals to 0, the nesting of the second opening bracket equals to 0 and the nesting of the third opening bracket equal to 1. So the total sum of nestings equals to 1.",[]104"There is an array with n elements a1, a2, ..., an and the number x.In one operation you can select some i (1 ≤ i ≤ n) and replace element ai with ai & x, where & denotes the bitwise and operation.You want the array to have at least two equal elements after applying some operations (possibly, none). In other words, there should be at least two distinct indices i ≠ j such that ai = aj. Determine whether it is possible to achieve and, if possible, the minimal number of operations to apply.",[]105"Vasya commutes by train every day. There are n train stations in the city, and at the i-th station it's possible to buy only tickets to stations from i + 1 to ai inclusive. No tickets are sold at the last station.Let ρi, j be the minimum number of tickets one needs to buy in order to get from stations i to station j. As Vasya is fond of different useless statistic he asks you to compute the sum of all values ρi, j among all pairs 1 ≤ i < j ≤ n.",[]106"Levko loves permutations very much. A permutation of length n is a sequence of distinct positive integers, each is at most n.Let’s assume that value gcd(a, b) shows the greatest common divisor of numbers a and b. Levko assumes that element pi of permutation p1, p2, ... , pn is good if gcd(i, pi) > 1. Levko considers a permutation beautiful, if it has exactly k good elements. Unfortunately, he doesn’t know any beautiful permutation. Your task is to help him to find at least one of them.","['math', 'number theory']"107"This is an interactive problem.Jury has hidden a permutation p of integers from 0 to n - 1. You know only the length n. Remind that in permutation all integers are distinct.Let b be the inverse permutation for p, i.e. pbi = i for all i. The only thing you can do is to ask xor of elements pi and bj, printing two indices i and j (not necessarily distinct). As a result of the query with indices i and j you'll get the value , where  denotes the xor operation. You can find the description of xor operation in notes.Note that some permutations can remain indistinguishable from the hidden one, even if you make all possible n2 queries. You have to compute the number of permutations indistinguishable from the hidden one, and print one of such permutations, making no more than 2n queries.The hidden permutation does not depend on your queries.",[]108"Recently Polycarp started to develop a text editor that works only with correct bracket sequences (abbreviated as CBS). Note that a bracket sequence is correct if it is possible to get a correct mathematical expression by adding ""+""-s and ""1""-s to it. For example, sequences ""(())()"", ""()"" and ""(()(()))"" are correct, while "")("", ""(()"" and ""(()))("" are not. Each bracket in CBS has a pair. For example, in ""(()(()))"":  1st bracket is paired with 8th,  2d bracket is paired with 3d,  3d bracket is paired with 2d,  4th bracket is paired with 7th,  5th bracket is paired with 6th,  6th bracket is paired with 5th,  7th bracket is paired with 4th,  8th bracket is paired with 1st. Polycarp's editor currently supports only three operations during the use of CBS. The cursor in the editor takes the whole position of one of the brackets (not the position between the brackets!). There are three operations being supported:  «L» — move the cursor one position to the left,  «R» — move the cursor one position to the right,  «D» — delete the bracket in which the cursor is located, delete the bracket it's paired to and all brackets between them (that is, delete a substring between the bracket in which the cursor is located and the one it's paired to). After the operation ""D"" the cursor moves to the nearest bracket to the right (of course, among the non-deleted). If there is no such bracket (that is, the suffix of the CBS was deleted), then the cursor moves to the nearest bracket to the left (of course, among the non-deleted). There are pictures illustrated several usages of operation ""D"" below.  All incorrect operations (shift cursor over the end of CBS, delete the whole CBS, etc.) are not supported by Polycarp's editor.Polycarp is very proud of his development, can you implement the functionality of his editor?",['strings']109"Arkady plays Gardenscapes a lot. Arkady wants to build two new fountains. There are n available fountains, for each fountain its beauty and cost are known. There are two types of money in the game: coins and diamonds, so each fountain cost can be either in coins or diamonds. No money changes between the types are allowed.Help Arkady to find two fountains with maximum total beauty so that he can buy both at the same time.",[]110"Polycarp is reading a book consisting of $$$n$$$ pages numbered from $$$1$$$ to $$$n$$$. Every time he finishes the page with the number divisible by $$$m$$$, he writes down the last digit of this page number. For example, if $$$n=15$$$ and $$$m=5$$$, pages divisible by $$$m$$$ are $$$5, 10, 15$$$. Their last digits are $$$5, 0, 5$$$ correspondingly, their sum is $$$10$$$.Your task is to calculate the sum of all digits Polycarp has written down.You have to answer $$$q$$$ independent queries.",['math']111"You are given an array $$$a$$$ of $$$n$$$ positive integers.You can use the following operation as many times as you like: select any integer $$$1 \le k \le n$$$ and do one of two things:   decrement by one $$$k$$$ of the first elements of the array.  decrement by one $$$k$$$ of the last elements of the array. For example, if $$$n=5$$$ and $$$a=[3,2,2,1,4]$$$, then you can apply one of the following operations to it (not all possible options are listed below):   decrement from the first two elements of the array. After this operation $$$a=[2, 1, 2, 1, 4]$$$;  decrement from the last three elements of the array. After this operation $$$a=[3, 2, 1, 0, 3]$$$;  decrement from the first five elements of the array. After this operation $$$a=[2, 1, 1, 0, 3]$$$; Determine if it is possible to make all the elements of the array equal to zero by applying a certain number of operations.",['math']112"A schoolboy named Vasya loves reading books on programming and mathematics. He has recently read an encyclopedia article that described the method of median smoothing (or median filter) and its many applications in science and engineering. Vasya liked the idea of the method very much, and he decided to try it in practice.Applying the simplest variant of median smoothing to the sequence of numbers a1, a2, ..., an will result a new sequence b1, b2, ..., bn obtained by the following algorithm:  b1 = a1, bn = an, that is, the first and the last number of the new sequence match the corresponding numbers of the original sequence.  For i = 2, ..., n - 1 value bi is equal to the median of three values ai - 1, ai and ai + 1. The median of a set of three numbers is the number that goes on the second place, when these three numbers are written in the non-decreasing order. For example, the median of the set 5, 1, 2 is number 2, and the median of set 1, 0, 1 is equal to 1.In order to make the task easier, Vasya decided to apply the method to sequences consisting of zeros and ones only.Having made the procedure once, Vasya looked at the resulting sequence and thought: what if I apply the algorithm to it once again, and then apply it to the next result, and so on? Vasya tried a couple of examples and found out that after some number of median smoothing algorithm applications the sequence can stop changing. We say that the sequence is stable, if it does not change when the median smoothing is applied to it.Now Vasya wonders, whether the sequence always eventually becomes stable. He asks you to write a program that, given a sequence of zeros and ones, will determine whether it ever becomes stable. Moreover, if it ever becomes stable, then you should determine what will it look like and how many times one needs to apply the median smoothing algorithm to initial sequence in order to obtain a stable one.",[]113"Kuzya started going to school. He was given math homework in which he was given an array $$$a$$$ of length $$$n$$$ and an array of symbols $$$b$$$ of length $$$n$$$, consisting of symbols '*' and '/'.Let's denote a path of calculations for a segment $$$[l; r]$$$ ($$$1 \le l \le r \le n$$$) in the following way:   Let $$$x=1$$$ initially. For every $$$i$$$ from $$$l$$$ to $$$r$$$ we will consequently do the following: if $$$b_i=$$$ '*', $$$x=x*a_i$$$, and if $$$b_i=$$$ '/', then $$$x=\frac{x}{a_i}$$$. Let's call a path of calculations for the segment $$$[l; r]$$$ a list of all $$$x$$$ that we got during the calculations (the number of them is exactly $$$r - l + 1$$$). For example, let $$$a=[7,$$$ $$$12,$$$ $$$3,$$$ $$$5,$$$ $$$4,$$$ $$$10,$$$ $$$9]$$$, $$$b=[/,$$$ $$$*,$$$ $$$/,$$$ $$$/,$$$ $$$/,$$$ $$$*,$$$ $$$*]$$$, $$$l=2$$$, $$$r=6$$$, then the path of calculations for that segment is $$$[12,$$$ $$$4,$$$ $$$0.8,$$$ $$$0.2,$$$ $$$2]$$$.Let's call a segment $$$[l;r]$$$ simple if the path of calculations for it contains only integer numbers. Kuzya needs to find the number of simple segments $$$[l;r]$$$ ($$$1 \le l \le r \le n$$$). Since he obviously has no time and no interest to do the calculations for each option, he asked you to write a program to get to find that number!",['number theory']114"As Sherlock Holmes was investigating a crime, he identified n suspects. He knows for sure that exactly one of them committed the crime. To find out which one did it, the detective lines up the suspects and numbered them from 1 to n. After that, he asked each one: ""Which one committed the crime?"". Suspect number i answered either ""The crime was committed by suspect number ai"", or ""Suspect number ai didn't commit the crime"". Also, the suspect could say so about himself (ai = i).Sherlock Holmes understood for sure that exactly m answers were the truth and all other answers were a lie. Now help him understand this: which suspect lied and which one told the truth?",[]115"You are given an undirected graph consisting of $$$n$$$ vertices and $$$n$$$ edges. It is guaranteed that the given graph is connected (i. e. it is possible to reach any vertex from any other vertex) and there are no self-loops and multiple edges in the graph.Your task is to calculate the number of simple paths of length at least $$$1$$$ in the given graph. Note that paths that differ only by their direction are considered the same (i. e. you have to calculate the number of undirected paths). For example, paths $$$[1, 2, 3]$$$ and $$$[3, 2, 1]$$$ are considered the same.You have to answer $$$t$$$ independent test cases.Recall that a path in the graph is a sequence of vertices $$$v_1, v_2, \ldots, v_k$$$ such that each pair of adjacent (consecutive) vertices in this sequence is connected by an edge. The length of the path is the number of edges in it. A simple path is such a path that all vertices in it are distinct.","['graphs', 'trees']"116"You are given an array of positive integers. While there are at least two equal elements, we will perform the following operation. We choose the smallest value $$$x$$$ that occurs in the array $$$2$$$ or more times. Take the first two occurrences of $$$x$$$ in this array (the two leftmost occurrences). Remove the left of these two occurrences, and the right one is replaced by the sum of this two values (that is, $$$2 \cdot x$$$).Determine how the array will look after described operations are performed.For example, consider the given array looks like $$$[3, 4, 1, 2, 2, 1, 1]$$$. It will be changed in the following way: $$$[3, 4, 1, 2, 2, 1, 1]~\rightarrow~[3, 4, 2, 2, 2, 1]~\rightarrow~[3, 4, 4, 2, 1]~\rightarrow~[3, 8, 2, 1]$$$.If the given array is look like $$$[1, 1, 3, 1, 1]$$$ it will be changed in the following way: $$$[1, 1, 3, 1, 1]~\rightarrow~[2, 3, 1, 1]~\rightarrow~[2, 3, 2]~\rightarrow~[3, 4]$$$.",[]117"You have a long fence which consists of $$$n$$$ sections. Unfortunately, it is not painted, so you decided to hire $$$q$$$ painters to paint it. $$$i$$$-th painter will paint all sections $$$x$$$ such that $$$l_i \le x \le r_i$$$.Unfortunately, you are on a tight budget, so you may hire only $$$q - 2$$$ painters. Obviously, only painters you hire will do their work.You want to maximize the number of painted sections if you choose $$$q - 2$$$ painters optimally. A section is considered painted if at least one painter paints it.",[]118"An agent called Cypher is decrypting a message, that contains a composite number $$$n$$$. All divisors of $$$n$$$, which are greater than $$$1$$$, are placed in a circle. Cypher can choose the initial order of numbers in the circle.In one move Cypher can choose two adjacent numbers in a circle and insert their least common multiple between them. He can do that move as many times as needed.A message is decrypted, if every two adjacent numbers are not coprime. Note that for such constraints it's always possible to decrypt the message.Find the minimal number of moves that Cypher should do to decrypt the message, and show the initial order of numbers in the circle for that.","['math', 'number theory']"119Let's define the following recurrence: $$$$$$a_{n+1} = a_{n} + minDigit(a_{n}) \cdot maxDigit(a_{n}).$$$$$$Here $$$minDigit(x)$$$ and $$$maxDigit(x)$$$ are the minimal and maximal digits in the decimal representation of $$$x$$$ without leading zeroes. For examples refer to notes.Your task is calculate $$$a_{K}$$$ for given $$$a_{1}$$$ and $$$K$$$.,['math']120"Mr. Chanek has a new game called Dropping Balls. Initially, Mr. Chanek has a grid $$$a$$$ of size $$$n \times m$$$Each cell $$$(x,y)$$$ contains an integer $$$a_{x,y}$$$ denoting the direction of how the ball will move.  $$$a_{x,y}=1$$$ — the ball will move to the right (the next cell is $$$(x, y + 1)$$$);  $$$a_{x,y}=2$$$ — the ball will move to the bottom (the next cell is $$$(x + 1, y)$$$);  $$$a_{x,y}=3$$$ — the ball will move to the left (the next cell is $$$(x, y - 1)$$$). Every time a ball leaves a cell $$$(x,y)$$$, the integer $$$a_{x,y}$$$ will change to $$$2$$$. Mr. Chanek will drop $$$k$$$ balls sequentially, each starting from the first row, and on the $$$c_1, c_2, \dots, c_k$$$-th ($$$1 \leq c_i \leq m$$$) columns.Determine in which column each ball will end up in (position of the ball after leaving the grid).",[]121"Recently Vova found $$$n$$$ candy wrappers. He remembers that he bought $$$x$$$ candies during the first day, $$$2x$$$ candies during the second day, $$$4x$$$ candies during the third day, $$$\dots$$$, $$$2^{k-1} x$$$ candies during the $$$k$$$-th day. But there is an issue: Vova remembers neither $$$x$$$ nor $$$k$$$ but he is sure that $$$x$$$ and $$$k$$$ are positive integers and $$$k > 1$$$.Vova will be satisfied if you tell him any positive integer $$$x$$$ so there is an integer $$$k>1$$$ that $$$x + 2x + 4x + \dots + 2^{k-1} x = n$$$. It is guaranteed that at least one solution exists. Note that $$$k > 1$$$.You have to answer $$$t$$$ independent test cases.",['math']122"You are given a bracket sequence $$$s$$$ of length $$$n$$$, where $$$n$$$ is even (divisible by two). The string $$$s$$$ consists of $$$\frac{n}{2}$$$ opening brackets '(' and $$$\frac{n}{2}$$$ closing brackets ')'.In one move, you can choose exactly one bracket and move it to the beginning of the string or to the end of the string (i.e. you choose some index $$$i$$$, remove the $$$i$$$-th character of $$$s$$$ and insert it before or after all remaining characters of $$$s$$$).Your task is to find the minimum number of moves required to obtain regular bracket sequence from $$$s$$$. It can be proved that the answer always exists under the given constraints.Recall what the regular bracket sequence is:  ""()"" is regular bracket sequence;  if $$$s$$$ is regular bracket sequence then ""("" + $$$s$$$ + "")"" is regular bracket sequence;  if $$$s$$$ and $$$t$$$ are regular bracket sequences then $$$s$$$ + $$$t$$$ is regular bracket sequence. For example, ""()()"", ""(())()"", ""(())"" and ""()"" are regular bracket sequences, but "")("", ""()("" and "")))"" are not.You have to answer $$$t$$$ independent test cases.",['strings']123"Professor Ibrahim has prepared the final homework for his algorithm’s class. He asked his students to implement the Posterization Image Filter.Their algorithm will be tested on an array of integers, where the $$$i$$$-th integer represents the color of the $$$i$$$-th pixel in the image. The image is in black and white, therefore the color of each pixel will be an integer between 0 and 255 (inclusive).To implement the filter, students are required to divide the black and white color range [0, 255] into groups of consecutive colors, and select one color in each group to be the group’s key. In order to preserve image details, the size of a group must not be greater than $$$k$$$, and each color should belong to exactly one group.Finally, the students will replace the color of each pixel in the array with that color’s assigned group key.To better understand the effect, here is an image of a basking turtle where the Posterization Filter was applied with increasing $$$k$$$ to the right.   To make the process of checking the final answer easier, Professor Ibrahim wants students to divide the groups and assign the keys in a way that produces the lexicographically smallest possible array.",['games']124"Recently, a start up by two students of a state university of city F gained incredible popularity. Now it's time to start a new company. But what do we call it?The market analysts came up with a very smart plan: the name of the company should be identical to its reflection in a mirror! In other words, if we write out the name of the company on a piece of paper in a line (horizontally, from left to right) with large English letters, then put this piece of paper in front of the mirror, then the reflection of the name in the mirror should perfectly match the line written on the piece of paper.There are many suggestions for the company name, so coming up to the mirror with a piece of paper for each name wouldn't be sensible. The founders of the company decided to automatize this process. They asked you to write a program that can, given a word, determine whether the word is a 'mirror' word or not.",[]125"You want to perform the combo on your opponent in one popular fighting game. The combo is the string $$$s$$$ consisting of $$$n$$$ lowercase Latin letters. To perform the combo, you have to press all buttons in the order they appear in $$$s$$$. I.e. if $$$s=$$$""abca"" then you have to press 'a', then 'b', 'c' and 'a' again.You know that you will spend $$$m$$$ wrong tries to perform the combo and during the $$$i$$$-th try you will make a mistake right after $$$p_i$$$-th button ($$$1 \le p_i < n$$$) (i.e. you will press first $$$p_i$$$ buttons right and start performing the combo from the beginning). It is guaranteed that during the $$$m+1$$$-th try you press all buttons right and finally perform the combo.I.e. if $$$s=$$$""abca"", $$$m=2$$$ and $$$p = [1, 3]$$$ then the sequence of pressed buttons will be 'a' (here you're making a mistake and start performing the combo from the beginning), 'a', 'b', 'c', (here you're making a mistake and start performing the combo from the beginning), 'a' (note that at this point you will not perform the combo because of the mistake), 'b', 'c', 'a'.Your task is to calculate for each button (letter) the number of times you'll press it.You have to answer $$$t$$$ independent test cases.",[]126"The blinds are known to consist of opaque horizontal stripes that can be rotated thus regulating the amount of light flowing in the room. There are n blind stripes with the width of 1 in the factory warehouse for blind production. The problem is that all of them are spare details from different orders, that is, they may not have the same length (it is even possible for them to have different lengths)Every stripe can be cut into two or more parts. The cuttings are made perpendicularly to the side along which the length is measured. Thus the cuttings do not change the width of a stripe but each of the resulting pieces has a lesser length (the sum of which is equal to the length of the initial stripe)After all the cuttings the blinds are constructed through consecutive joining of several parts, similar in length, along sides, along which length is measured. Also, apart from the resulting pieces an initial stripe can be used as a blind if it hasn't been cut. It is forbidden to construct blinds in any other way.Thus, if the blinds consist of k pieces each d in length, then they are of form of a rectangle of k × d bourlemeters. Your task is to find for what window possessing the largest possible area the blinds can be made from the given stripes if on technical grounds it is forbidden to use pieces shorter than l bourlemeter. The window is of form of a rectangle with side lengths as positive integers.",[]127"On the board, Bob wrote $$$n$$$ positive integers in base $$$10$$$ with sum $$$s$$$ (i. e. in decimal numeral system). Alice sees the board, but accidentally interprets the numbers on the board as base-$$$11$$$ integers and adds them up (in base $$$11$$$).What numbers should Bob write on the board, so Alice's sum is as large as possible?",['math']128"AquaMoon has $$$n$$$ friends. They stand in a row from left to right, and the $$$i$$$-th friend from the left wears a T-shirt with a number $$$a_i$$$ written on it. Each friend has a direction (left or right). In the beginning, the direction of each friend is right.AquaMoon can make some operations on friends. On each operation, AquaMoon can choose two adjacent friends and swap their positions. After each operation, the direction of both chosen friends will also be flipped: left to right and vice versa.AquaMoon hopes that after some operations, the numbers written on the T-shirt of $$$n$$$ friends in the row, read from left to right, become non-decreasing. Also she wants, that all friends will have a direction of right at the end. Please find if it is possible.",[]129"The position of the leftmost maximum on the segment $$$[l; r]$$$ of array $$$x = [x_1, x_2, \ldots, x_n]$$$ is the smallest integer $$$i$$$ such that $$$l \le i \le r$$$ and $$$x_i = \max(x_l, x_{l+1}, \ldots, x_r)$$$.You are given an array $$$a = [a_1, a_2, \ldots, a_n]$$$ of length $$$n$$$. Find the number of integer arrays $$$b = [b_1, b_2, \ldots, b_n]$$$ of length $$$n$$$ that satisfy the following conditions:   $$$1 \le b_i \le m$$$ for all $$$1 \le i \le n$$$;  for all pairs of integers $$$1 \le l \le r \le n$$$, the position of the leftmost maximum on the segment $$$[l; r]$$$ of the array $$$b$$$ is equal to the position of the leftmost maximum on the segment $$$[l; r]$$$ of the array $$$a$$$. Since the answer might be very large, print its remainder modulo $$$10^9+7$$$.","['math', 'trees']"130"""The Chamber of Secrets has been opened again"" — this news has spread all around Hogwarts and some of the students have been petrified due to seeing the basilisk. Dumbledore got fired and now Harry is trying to enter the Chamber of Secrets. These aren't good news for Lord Voldemort. The problem is, he doesn't want anybody to be able to enter the chamber. The Dark Lord is going to be busy sucking life out of Ginny.The Chamber of Secrets is an n × m rectangular grid in which some of the cells are columns. A light ray (and a basilisk's gaze) passes through the columns without changing its direction. But with some spell we can make a column magic to reflect the light ray (or the gaze) in all four directions when it receives the ray. This is shown in the figure below.   The left light ray passes through a regular column, and the right ray — through the magic column.  The basilisk is located at the right side of the lower right cell of the grid and is looking to the left (in the direction of the lower left cell). According to the legend, anyone who meets a basilisk's gaze directly dies immediately. But if someone meets a basilisk's gaze through a column, this person will get petrified. We know that the door to the Chamber is located on the left side of the upper left corner of the grid and anyone who wants to enter will look in the direction of its movement (in the direction of the upper right cell) from that position.   This figure illustrates the first sample test.  Given the dimensions of the chamber and the location of regular columns, Lord Voldemort has asked you to find the minimum number of columns that we need to make magic so that anyone who wants to enter the chamber would be petrified or just declare that it's impossible to secure the chamber.",[]131"Zibi is a competitive programming coach. There are $$$n$$$ competitors who want to be prepared well. The training contests are quite unusual – there are two people in a team, two problems, and each competitor will code exactly one of them. Of course, people in one team will code different problems.Rules of scoring also aren't typical. The first problem is always an implementation problem: you have to implement some well-known algorithm very fast and the time of your typing is rated. The second one is an awful geometry task and you just have to get it accepted in reasonable time. Here the length and difficulty of your code are important. After that, Zibi will give some penalty points (possibly negative) for each solution and the final score of the team is the sum of them (the less the score is, the better).We know that the $$$i$$$-th competitor will always have score $$$x_i$$$ when he codes the first task and $$$y_i$$$ when he codes the second task. We can assume, that all competitors know each other's skills and during the contest distribute the problems in the way that minimizes their final score. Remember that each person codes exactly one problem in a contest.Zibi wants all competitors to write a contest with each other. However, there are $$$m$$$ pairs of people who really don't like to cooperate and they definitely won't write a contest together. Still, the coach is going to conduct trainings for all possible pairs of people, such that the people in pair don't hate each other. The coach is interested for each participant, what will be his or her sum of scores of all teams he trained in?",['math']132"On February 14 Denis decided to give Valentine to Nastya and did not come up with anything better than to draw a huge red heart on the door of the length $$$k$$$ ($$$k \ge 3$$$). Nastya was very confused by this present, so she decided to break the door, throwing it on the mountains.Mountains are described by a sequence of heights $$$a_1, a_2, \dots, a_n$$$ in order from left to right ($$$k \le n$$$). It is guaranteed that neighboring heights are not equal to each other (that is, $$$a_i \ne a_{i+1}$$$ for all $$$i$$$ from $$$1$$$ to $$$n-1$$$).Peaks of mountains on the segment $$$[l,r]$$$ (from $$$l$$$ to $$$r$$$) are called indexes $$$i$$$ such that $$$l < i < r$$$, $$$a_{i - 1} < a_i$$$ and $$$a_i > a_{i + 1}$$$. It is worth noting that the boundary indexes $$$l$$$ and $$$r$$$ for the segment are not peaks. For example, if $$$n=8$$$ and $$$a=[3,1,4,1,5,9,2,6]$$$, then the segment $$$[1,8]$$$ has only two peaks (with indexes $$$3$$$ and $$$6$$$), and there are no peaks on the segment $$$[3, 6]$$$.To break the door, Nastya throws it to a segment $$$[l,l+k-1]$$$ of consecutive mountains of length $$$k$$$ ($$$1 \le l \le n-k+1$$$). When the door touches the peaks of the mountains, it breaks into two parts, after that these parts will continue to fall in different halves and also break into pieces when touching the peaks of the mountains, and so on. Formally, the number of parts that the door will break into will be equal to $$$p+1$$$, where $$$p$$$ is the number of peaks on the segment $$$[l,l+k-1]$$$.Nastya wants to break it into as many pieces as possible. Help her choose such a segment of mountains $$$[l, l+k-1]$$$ that the number of peaks on it is maximum. If there are several optimal segments, Nastya wants to find one for which the value $$$l$$$ is minimal.Formally, you need to choose a segment of mountains $$$[l, l+k-1]$$$ that has the maximum number of peaks. Among all such segments, you need to find the segment that has the minimum possible value $$$l$$$.",[]133"  William really likes the cellular automaton called ""Game of Life"" so he decided to make his own version. For simplicity, William decided to define his cellular automaton on an array containing $$$n$$$ cells, with each cell either being alive or dead.Evolution of the array in William's cellular automaton occurs iteratively in the following way:  If the element is dead and it has exactly $$$1$$$ alive neighbor in the current state of the array, then on the next iteration it will become alive. For an element at index $$$i$$$ the neighbors would be elements with indices $$$i - 1$$$ and $$$i + 1$$$. If there is no element at that index, it is considered to be a dead neighbor.  William is a humane person so all alive elements stay alive. Check the note section for examples of the evolution.You are given some initial state of all elements and you need to help William find the state of the array after $$$m$$$ iterations of evolution.",[]134"The Fair Nut likes kvass very much. On his birthday parents presented him $$$n$$$ kegs of kvass. There are $$$v_i$$$ liters of kvass in the $$$i$$$-th keg. Each keg has a lever. You can pour your glass by exactly $$$1$$$ liter pulling this lever. The Fair Nut likes this drink very much, so he wants to pour his glass by $$$s$$$ liters of kvass. But he wants to do it, so kvass level in the least keg is as much as possible.Help him find out how much kvass can be in the least keg or define it's not possible to pour his glass by $$$s$$$ liters of kvass.",[]135"At the first holiday in spring, the town Shortriver traditionally conducts a flower festival. Townsfolk wear traditional wreaths during these festivals. Each wreath contains exactly $$$k$$$ flowers.The work material for the wreaths for all $$$n$$$ citizens of Shortriver is cut from the longest flowered liana that grew in the town that year. Liana is a sequence $$$a_1$$$, $$$a_2$$$, ..., $$$a_m$$$, where $$$a_i$$$ is an integer that denotes the type of flower at the position $$$i$$$. This year the liana is very long ($$$m \ge n \cdot k$$$), and that means every citizen will get a wreath.Very soon the liana will be inserted into a special cutting machine in order to make work material for wreaths. The machine works in a simple manner: it cuts $$$k$$$ flowers from the beginning of the liana, then another $$$k$$$ flowers and so on. Each such piece of $$$k$$$ flowers is called a workpiece. The machine works until there are less than $$$k$$$ flowers on the liana.Diana has found a weaving schematic for the most beautiful wreath imaginable. In order to weave it, $$$k$$$ flowers must contain flowers of types $$$b_1$$$, $$$b_2$$$, ..., $$$b_s$$$, while other can be of any type. If a type appears in this sequence several times, there should be at least that many flowers of that type as the number of occurrences of this flower in the sequence. The order of the flowers in a workpiece does not matter.Diana has a chance to remove some flowers from the liana before it is inserted into the cutting machine. She can remove flowers from any part of the liana without breaking liana into pieces. If Diana removes too many flowers, it may happen so that some of the citizens do not get a wreath. Could some flowers be removed from the liana so that at least one workpiece would conform to the schematic and machine would still be able to create at least $$$n$$$ workpieces?",[]136"You are given $$$n$$$ sticks with positive integral length $$$a_1, a_2, \ldots, a_n$$$.You can perform the following operation any number of times (possibly zero):   choose one stick, then either increase or decrease its length by $$$1$$$. After each operation, all sticks should have positive lengths. What is the minimum number of operations that you have to perform such that it is possible to select three of the $$$n$$$ sticks and use them without breaking to form an equilateral triangle?An equilateral triangle is a triangle where all of its three sides have the same length.",[]137"Even if it's a really easy question, she won't be able to answer it— Perfect Memento in Strict SenseCirno's perfect bitmasks classroom has just started!Cirno gave her students a positive integer $$$x$$$. As an assignment, her students need to find the minimum positive integer $$$y$$$, which satisfies the following two conditions:$$$$$$x\ \texttt{and}\ y > 0$$$$$$ $$$$$$x\ \texttt{xor}\ y > 0$$$$$$Where $$$\texttt{and}$$$ is the bitwise AND operation, and $$$\texttt{xor}$$$ is the bitwise XOR operation.Among the students was Mystia, who was truly baffled by all these new operators. Please help her!",[]138"Grisha come to a contest and faced the following problem.You are given an array of size $$$n$$$, initially consisting of zeros. The elements of the array are enumerated from $$$1$$$ to $$$n$$$. You perform $$$q$$$ operations on the array. The $$$i$$$-th operation is described with three integers $$$l_i$$$, $$$r_i$$$ and $$$x_i$$$ ($$$1 \leq l_i \leq r_i \leq n$$$, $$$1 \leq x_i \leq n$$$) and means that you should add $$$x_i$$$ to each of the elements with indices $$$l_i, l_i + 1, \ldots, r_i$$$. After all operations you should find the maximum in the array.Grisha is clever, so he solved the problem quickly.However something went wrong inside his head and now he thinks of the following question: ""consider we applied some subset of the operations to the array. What are the possible values of the maximum in the array?""Help Grisha, find all integers $$$y$$$ between $$$1$$$ and $$$n$$$ such that if you apply some subset (possibly empty) of the operations, then the maximum in the array becomes equal to $$$y$$$.",[]139"After you had helped George and Alex to move in the dorm, they went to help their friend Fedor play a new computer game «Call of Soldiers 3».The game has (m + 1) players and n types of soldiers in total. Players «Call of Soldiers 3» are numbered form 1 to (m + 1). Types of soldiers are numbered from 0 to n - 1. Each player has an army. Army of the i-th player can be described by non-negative integer xi. Consider binary representation of xi: if the j-th bit of number xi equal to one, then the army of the i-th player has soldiers of the j-th type. Fedor is the (m + 1)-th player of the game. He assume that two players can become friends if their armies differ in at most k types of soldiers (in other words, binary representations of the corresponding numbers differ in at most k bits). Help Fedor and count how many players can become his friends.",[]140"You are given two arrays of integers $$$a_1, a_2, \ldots, a_n$$$ and $$$b_1, b_2, \ldots, b_n$$$.Let's define a transformation of the array $$$a$$$:  Choose any non-negative integer $$$k$$$ such that $$$0 \le k \le n$$$.  Choose $$$k$$$ distinct array indices $$$1 \le i_1 < i_2 < \ldots < i_k \le n$$$.  Add $$$1$$$ to each of $$$a_{i_1}, a_{i_2}, \ldots, a_{i_k}$$$, all other elements of array $$$a$$$ remain unchanged.  Permute the elements of array $$$a$$$ in any order. Is it possible to perform some transformation of the array $$$a$$$ exactly once, so that the resulting array is equal to $$$b$$$?",['math']141"Long story short, shashlik is Miroslav's favorite food. Shashlik is prepared on several skewers simultaneously. There are two states for each skewer: initial and turned over.This time Miroslav laid out $$$n$$$ skewers parallel to each other, and enumerated them with consecutive integers from $$$1$$$ to $$$n$$$ in order from left to right. For better cooking, he puts them quite close to each other, so when he turns skewer number $$$i$$$, it leads to turning $$$k$$$ closest skewers from each side of the skewer $$$i$$$, that is, skewers number $$$i - k$$$, $$$i - k + 1$$$, ..., $$$i - 1$$$, $$$i + 1$$$, ..., $$$i + k - 1$$$, $$$i + k$$$ (if they exist). For example, let $$$n = 6$$$ and $$$k = 1$$$. When Miroslav turns skewer number $$$3$$$, then skewers with numbers $$$2$$$, $$$3$$$, and $$$4$$$ will come up turned over. If after that he turns skewer number $$$1$$$, then skewers number $$$1$$$, $$$3$$$, and $$$4$$$ will be turned over, while skewer number $$$2$$$ will be in the initial position (because it is turned again).As we said before, the art of cooking requires perfect timing, so Miroslav wants to turn over all $$$n$$$ skewers with the minimal possible number of actions. For example, for the above example $$$n = 6$$$ and $$$k = 1$$$, two turnings are sufficient: he can turn over skewers number $$$2$$$ and $$$5$$$.Help Miroslav turn over all $$$n$$$ skewers.",['math']142"Vasya had three strings $$$a$$$, $$$b$$$ and $$$s$$$, which consist of lowercase English letters. The lengths of strings $$$a$$$ and $$$b$$$ are equal to $$$n$$$, the length of the string $$$s$$$ is equal to $$$m$$$. Vasya decided to choose a substring of the string $$$a$$$, then choose a substring of the string $$$b$$$ and concatenate them. Formally, he chooses a segment $$$[l_1, r_1]$$$ ($$$1 \leq l_1 \leq r_1 \leq n$$$) and a segment $$$[l_2, r_2]$$$ ($$$1 \leq l_2 \leq r_2 \leq n$$$), and after concatenation he obtains a string $$$a[l_1, r_1] + b[l_2, r_2] = a_{l_1} a_{l_1 + 1} \ldots a_{r_1} b_{l_2} b_{l_2 + 1} \ldots b_{r_2}$$$.Now, Vasya is interested in counting number of ways to choose those segments adhering to the following conditions:  segments $$$[l_1, r_1]$$$ and $$$[l_2, r_2]$$$ have non-empty intersection, i.e. there exists at least one integer $$$x$$$, such that $$$l_1 \leq x \leq r_1$$$ and $$$l_2 \leq x \leq r_2$$$;  the string $$$a[l_1, r_1] + b[l_2, r_2]$$$ is equal to the string $$$s$$$. ",['strings']143"Suppose you have two polynomials  and . Then polynomial  can be uniquely represented in the following way:This can be done using long division. Here,  denotes the degree of polynomial P(x).  is called the remainder of division of polynomial  by polynomial , it is also denoted as . Since there is a way to divide polynomials with remainder, we can define Euclid's algorithm of finding the greatest common divisor of two polynomials. The algorithm takes two polynomials . If the polynomial  is zero, the result is , otherwise the result is the value the algorithm returns for pair . On each step the degree of the second argument decreases, so the algorithm works in finite number of steps. But how large that number could be? You are to answer this question. You are given an integer n. You have to build two polynomials with degrees not greater than n, such that their coefficients are integers not exceeding 1 by their absolute value, the leading coefficients (ones with the greatest power of x) are equal to one, and the described Euclid's algorithm performs exactly n steps finding their greatest common divisor. Moreover, the degree of the first polynomial should be greater than the degree of the second. By a step of the algorithm we mean the transition from pair  to pair . ",['math']144"Volodya and Vlad play the following game. There are k pies at the cells of n  ×  m board. Each turn Volodya moves one pie to the neighbouring (by side) cell. If the pie lies at the border of the board then Volodya can move it outside the board, get the pie and win. After Volodya's move, Vlad bans some edge at the border of the board of length 1 (between two knots of the board) so that Volodya is not able to move the pie outside the board through this edge anymore. The question is: will Volodya win this game? We suppose both players follow the optimal strategy.",['games']145"As Will is stuck in the Upside Down, he can still communicate with his mom, Joyce, through the Christmas lights (he can turn them on and off with his mind). He can't directly tell his mom where he is, because the monster that took him to the Upside Down will know and relocate him.   Thus, he came up with a puzzle to tell his mom his coordinates. His coordinates are the answer to the following problem.A string consisting only of parentheses ('(' and ')') is called a bracket sequence. Some bracket sequence are called correct bracket sequences. More formally:  Empty string is a correct bracket sequence.  if s is a correct bracket sequence, then (s) is also a correct bracket sequence.  if s and t are correct bracket sequences, then st (concatenation of s and t) is also a correct bracket sequence. A string consisting of parentheses and question marks ('?') is called pretty if and only if there's a way to replace each question mark with either '(' or ')' such that the resulting string is a non-empty correct bracket sequence.Will gave his mom a string s consisting of parentheses and question marks (using Morse code through the lights) and his coordinates are the number of pairs of integers (l, r) such that 1 ≤ l ≤ r ≤ |s| and the string slsl + 1... sr is pretty, where si is i-th character of s.Joyce doesn't know anything about bracket sequences, so she asked for your help.",['math']146"Professor GukiZ has two arrays of integers, a and b. Professor wants to make the sum of the elements in the array a sa as close as possible to the sum of the elements in the array b sb. So he wants to minimize the value v = |sa - sb|.In one operation professor can swap some element from the array a and some element from the array b. For example if the array a is [5, 1, 3, 2, 4] and the array b is [3, 3, 2] professor can swap the element 5 from the array a and the element 2 from the array b and get the new array a [2, 1, 3, 2, 4] and the new array b [3, 3, 5].Professor doesn't want to make more than two swaps. Find the minimal value v and some sequence of no more than two swaps that will lead to the such value v. Professor makes swaps one by one, each new swap he makes with the new arrays a and b.",[]147"There are $$$n$$$ piranhas with sizes $$$a_1, a_2, \ldots, a_n$$$ in the aquarium. Piranhas are numbered from left to right in order they live in the aquarium.Scientists of the Berland State University want to find if there is dominant piranha in the aquarium. The piranha is called dominant if it can eat all the other piranhas in the aquarium (except itself, of course). Other piranhas will do nothing while the dominant piranha will eat them.Because the aquarium is pretty narrow and long, the piranha can eat only one of the adjacent piranhas during one move. Piranha can do as many moves as it needs (or as it can). More precisely:   The piranha $$$i$$$ can eat the piranha $$$i-1$$$ if the piranha $$$i-1$$$ exists and $$$a_{i - 1} < a_i$$$.  The piranha $$$i$$$ can eat the piranha $$$i+1$$$ if the piranha $$$i+1$$$ exists and $$$a_{i + 1} < a_i$$$. When the piranha $$$i$$$ eats some piranha, its size increases by one ($$$a_i$$$ becomes $$$a_i + 1$$$).Your task is to find any dominant piranha in the aquarium or determine if there are no such piranhas.Note that you have to find any (exactly one) dominant piranha, you don't have to find all of them.For example, if $$$a = [5, 3, 4, 4, 5]$$$, then the third piranha can be dominant. Consider the sequence of its moves:   The piranha eats the second piranha and $$$a$$$ becomes $$$[5, \underline{5}, 4, 5]$$$ (the underlined piranha is our candidate).  The piranha eats the third piranha and $$$a$$$ becomes $$$[5, \underline{6}, 5]$$$.  The piranha eats the first piranha and $$$a$$$ becomes $$$[\underline{7}, 5]$$$.  The piranha eats the second piranha and $$$a$$$ becomes $$$[\underline{8}]$$$. You have to answer $$$t$$$ independent test cases.",[]148"There is a weighted tree with $$$n$$$ nodes and $$$n-1$$$ edges. The nodes are conveniently labeled from $$$1$$$ to $$$n$$$. The weights are positive integers at most $$$100$$$. Define the distance between two nodes to be the sum of edges on the unique path between the nodes. You would like to find the diameter of the tree. Diameter is the maximum distance between a pair of nodes.Unfortunately, the tree isn't given to you, but you can ask some questions about it. In one question, you can specify two nonempty disjoint sets of nodes $$$p$$$ and $$$q$$$, and the judge will return the maximum distance between a node in $$$p$$$ and a node in $$$q$$$. In the words, maximum distance between $$$x$$$ and $$$y$$$, where $$$x \in p$$$ and $$$y \in q$$$. After asking not more than $$$9$$$ questions, you must report the maximum distance between any pair of nodes.",['graphs']149"You are given an array of integers $$$a_1, a_2, \ldots, a_n$$$.You can do the following operation any number of times (possibly zero):   Choose any index $$$i$$$ and set $$$a_i$$$ to any integer (positive, negative or $$$0$$$). What is the minimum number of operations needed to turn $$$a$$$ into an arithmetic progression? The array $$$a$$$ is an arithmetic progression if $$$a_{i+1}-a_i=a_i-a_{i-1}$$$ for any $$$2 \leq i \leq n-1$$$.","['math', 'graphs']"150"You are given two positive integers $$$n$$$ ($$$1 \le n \le 10^9$$$) and $$$k$$$ ($$$1 \le k \le 100$$$). Represent the number $$$n$$$ as the sum of $$$k$$$ positive integers of the same parity (have the same remainder when divided by $$$2$$$).In other words, find $$$a_1, a_2, \ldots, a_k$$$ such that all $$$a_i>0$$$, $$$n = a_1 + a_2 + \ldots + a_k$$$ and either all $$$a_i$$$ are even or all $$$a_i$$$ are odd at the same time.If such a representation does not exist, then report it.",['math']151"In this problem, we will deal with binary strings. Each character of a binary string is either a 0 or a 1. We will also deal with substrings; recall that a substring is a contiguous subsequence of a string. We denote the substring of string $$$s$$$ starting from the $$$l$$$-th character and ending with the $$$r$$$-th character as $$$s[l \dots r]$$$. The characters of each string are numbered from $$$1$$$.We can perform several operations on the strings we consider. Each operation is to choose a substring of our string and replace it with another string. There are two possible types of operations: replace 011 with 110, or replace 110 with 011. For example, if we apply exactly one operation to the string 110011110, it can be transformed into 011011110, 110110110, or 110011011.Binary string $$$a$$$ is considered reachable from binary string $$$b$$$ if there exists a sequence $$$s_1$$$, $$$s_2$$$, ..., $$$s_k$$$ such that $$$s_1 = a$$$, $$$s_k = b$$$, and for every $$$i \in [1, k - 1]$$$, $$$s_i$$$ can be transformed into $$$s_{i + 1}$$$ using exactly one operation. Note that $$$k$$$ can be equal to $$$1$$$, i. e., every string is reachable from itself.You are given a string $$$t$$$ and $$$q$$$ queries to it. Each query consists of three integers $$$l_1$$$, $$$l_2$$$ and $$$len$$$. To answer each query, you have to determine whether $$$t[l_1 \dots l_1 + len - 1]$$$ is reachable from $$$t[l_2 \dots l_2 + len - 1]$$$.",['strings']152"Your friend Ivan asked you to help him rearrange his desktop. The desktop can be represented as a rectangle matrix of size $$$n \times m$$$ consisting of characters '.' (empty cell of the desktop) and '*' (an icon).The desktop is called good if all its icons are occupying some prefix of full columns and, possibly, the prefix of the next column (and there are no icons outside this figure). In other words, some amount of first columns will be filled with icons and, possibly, some amount of first cells of the next (after the last full column) column will be also filled with icons (and all the icons on the desktop belong to this figure). This is pretty much the same as the real life icons arrangement.In one move, you can take one icon and move it to any empty cell in the desktop.Ivan loves to add some icons to his desktop and remove them from it, so he is asking you to answer $$$q$$$ queries: what is the minimum number of moves required to make the desktop good after adding/removing one icon?Note that queries are permanent and change the state of the desktop.",[]153"Treeland is a country in which there are n towns connected by n - 1 two-way road such that it's possible to get from any town to any other town. In Treeland there are 2k universities which are located in different towns. Recently, the president signed the decree to connect universities by high-speed network.The Ministry of Education understood the decree in its own way and decided that it was enough to connect each university with another one by using a cable. Formally, the decree will be done! To have the maximum sum in the budget, the Ministry decided to divide universities into pairs so that the total length of the required cable will be maximum. In other words, the total distance between universities in k pairs should be as large as possible. Help the Ministry to find the maximum total distance. Of course, each university should be present in only one pair. Consider that all roads have the same length which is equal to 1. ","['graphs', 'trees']"154"The problem uses a simplified TCP/IP address model, please read the statement carefully.An IP address is a 32-bit integer, represented as a group of four decimal 8-bit integers (without leading zeroes), separated by commas. For example, record 0.255.1.123 shows a correct IP address and records 0.256.1.123 and 0.255.1.01 do not. In the given problem an arbitrary group of four 8-bit integers is a correct IP address.Our hero Polycarpus still works as a system administrator in some large corporation. He likes beautiful IP addresses. To check if some IP address is beautiful, he should do the following:  write out in a line four 8-bit numbers of the IP address, without the commas;  check if the resulting string is a palindrome. Let us remind you that a palindrome is a string that reads the same from right to left and from left to right.For example, IP addresses 12.102.20.121 and 0.3.14.130 are beautiful (as strings ""1210220121"" and ""0314130"" are palindromes), and IP addresses 1.20.20.1 and 100.4.4.1 are not.Polycarpus wants to find all beautiful IP addresses that have the given set of digits. Each digit from the set must occur in the IP address at least once. IP address must not contain any other digits. Help him to cope with this difficult task.",[]155"Author has gone out of the stories about Vasiliy, so here is just a formal task description.You are given q queries and a multiset A, initially containing only integer 0. There are three types of queries:  ""+ x"" — add integer x to multiset A. ""- x"" — erase one occurrence of integer x from multiset A. It's guaranteed that at least one x is present in the multiset A before this query. ""? x"" — you are given integer x and need to compute the value , i.e. the maximum value of bitwise exclusive OR (also know as XOR) of integer x and some integer y from the multiset A.Multiset is a set, where equal elements are allowed.",['trees']156"You are given a directed acyclic graph (a directed graph that does not contain cycles) of $$$n$$$ vertices and $$$m$$$ arcs. The $$$i$$$-th arc leads from the vertex $$$x_i$$$ to the vertex $$$y_i$$$ and has the weight $$$w_i$$$.Your task is to select an integer $$$a_v$$$ for each vertex $$$v$$$, and then write a number $$$b_i$$$ on each arcs $$$i$$$ such that $$$b_i = a_{x_i} - a_{y_i}$$$. You must select the numbers so that:  all $$$b_i$$$ are positive;  the value of the expression $$$\sum \limits_{i = 1}^{m} w_i b_i$$$ is the lowest possible. It can be shown that for any directed acyclic graph with non-negative $$$w_i$$$, such a way to choose numbers exists.","['math', 'graphs']"157"She is skilled in all kinds of magics, and is keen on inventing new one.—Perfect Memento in Strict SensePatchouli is making a magical talisman. She initially has $$$n$$$ magical tokens. Their magical power can be represented with positive integers $$$a_1, a_2, \ldots, a_n$$$. Patchouli may perform the following two operations on the tokens.  Fusion: Patchouli chooses two tokens, removes them, and creates a new token with magical power equal to the sum of the two chosen tokens.  Reduction: Patchouli chooses a token with an even value of magical power $$$x$$$, removes it and creates a new token with magical power equal to $$$\frac{x}{2}$$$. Tokens are more effective when their magical powers are odd values. Please help Patchouli to find the minimum number of operations she needs to make magical powers of all tokens odd values.",[]158"The annual college sports-ball tournament is approaching, which for trademark reasons we'll refer to as Third Month Insanity. There are a total of 2N teams participating in the tournament, numbered from 1 to 2N. The tournament lasts N rounds, with each round eliminating half the teams. The first round consists of 2N - 1 games, numbered starting from 1. In game i, team 2·i - 1 will play against team 2·i. The loser is eliminated and the winner advances to the next round (there are no ties). Each subsequent round has half as many games as the previous round, and in game i the winner of the previous round's game 2·i - 1 will play against the winner of the previous round's game 2·i.Every year the office has a pool to see who can create the best bracket. A bracket is a set of winner predictions for every game. For games in the first round you may predict either team to win, but for games in later rounds the winner you predict must also be predicted as a winner in the previous round. Note that the bracket is fully constructed before any games are actually played. Correct predictions in the first round are worth 1 point, and correct predictions in each subsequent round are worth twice as many points as the previous, so correct predictions in the final game are worth 2N - 1 points.For every pair of teams in the league, you have estimated the probability of each team winning if they play against each other. Now you want to construct a bracket with the maximum possible expected score.","['trees', 'probabilities']"159"A sequence of $$$n$$$ non-negative integers ($$$n \ge 2$$$) $$$a_1, a_2, \dots, a_n$$$ is called good if for all $$$i$$$ from $$$1$$$ to $$$n-1$$$ the following condition holds true: $$$$$$a_1 \: \& \: a_2 \: \& \: \dots \: \& \: a_i = a_{i+1} \: \& \: a_{i+2} \: \& \: \dots \: \& \: a_n,$$$$$$ where $$$\&$$$ denotes the bitwise AND operation.You are given an array $$$a$$$ of size $$$n$$$ ($$$n \geq 2$$$). Find the number of permutations $$$p$$$ of numbers ranging from $$$1$$$ to $$$n$$$, for which the sequence $$$a_{p_1}$$$, $$$a_{p_2}$$$, ... ,$$$a_{p_n}$$$ is good. Since this number can be large, output it modulo $$$10^9+7$$$.",['math']160"You know that the Martians use a number system with base k. Digit b (0 ≤ b < k) is considered lucky, as the first contact between the Martians and the Earthlings occurred in year b (by Martian chronology).A digital root d(x) of number x is a number that consists of a single digit, resulting after cascading summing of all digits of number x. Word ""cascading"" means that if the first summing gives us a number that consists of several digits, then we sum up all digits again, and again, until we get a one digit number.For example, d(35047) = d((3 + 5 + 0 + 4)7) = d(157) = d((1 + 5)7) = d(67) = 67. In this sample the calculations are performed in the 7-base notation.If a number's digital root equals b, the Martians also call this number lucky.You have string s, which consists of n digits in the k-base notation system. Your task is to find, how many distinct substrings of the given string are lucky numbers. Leading zeroes are permitted in the numbers.Note that substring s[i... j] of the string s = a1a2... an (1 ≤ i ≤ j ≤ n) is the string aiai + 1... aj. Two substrings s[i1... j1] and s[i2... j2] of the string s are different if either i1 ≠ i2 or j1 ≠ j2.","['math', 'number theory']"161"Petya was late for the lesson too. The teacher gave him an additional task. For some array a Petya should find the number of different ways to select non-empty subset of elements from it in such a way that their product is equal to a square of some integer.Two ways are considered different if sets of indexes of elements chosen by these ways are different.Since the answer can be very large, you should find the answer modulo 109 + 7.",['math']162"One day Vasya got hold of information on the Martian dollar course in bourles for the next n days. The buying prices and the selling prices for one dollar on day i are the same and are equal to ai. Vasya has b bourles. He can buy a certain number of dollars and then sell it no more than once in n days. According to Martian laws, one can buy only an integer number of dollars. Which maximal sum of money in bourles can Vasya get by the end of day n?",[]163"During the ""Russian Code Cup"" programming competition, the testing system stores all sent solutions for each participant. We know that many participants use random numbers in their programs and are often sent several solutions with the same source code to check.Each participant is identified by some unique positive integer k, and each sent solution A is characterized by two numbers: x — the number of different solutions that are sent before the first solution identical to A, and k — the number of the participant, who is the author of the solution. Consequently, all identical solutions have the same x.It is known that the data in the testing system are stored in the chronological order, that is, if the testing system has a solution with number x (x > 0) of the participant with number k, then the testing system has a solution with number x - 1 of the same participant stored somewhere before.During the competition the checking system crashed, but then the data of the submissions of all participants have been restored. Now the jury wants to verify that the recovered data is in chronological order. Help the jury to do so.",[]164"There are $$$n$$$ positive integers $$$a_1, a_2, \dots, a_n$$$. For the one move you can choose any even value $$$c$$$ and divide by two all elements that equal $$$c$$$.For example, if $$$a=[6,8,12,6,3,12]$$$ and you choose $$$c=6$$$, and $$$a$$$ is transformed into $$$a=[3,8,12,3,3,12]$$$ after the move.You need to find the minimal number of moves for transforming $$$a$$$ to an array of only odd integers (each element shouldn't be divisible by $$$2$$$).",['number theory']165"A permutation is a sequence of $$$n$$$ integers from $$$1$$$ to $$$n$$$, in which all numbers occur exactly once. For example, $$$[1]$$$, $$$[3, 5, 2, 1, 4]$$$, $$$[1, 3, 2]$$$ are permutations, and $$$[2, 3, 2]$$$, $$$[4, 3, 1]$$$, $$$[0]$$$ are not.Polycarp was presented with a permutation $$$p$$$ of numbers from $$$1$$$ to $$$n$$$. However, when Polycarp came home, he noticed that in his pocket, the permutation $$$p$$$ had turned into an array $$$q$$$ according to the following rule:   $$$q_i = \max(p_1, p_2, \ldots, p_i)$$$. Now Polycarp wondered what lexicographically minimal and lexicographically maximal permutations could be presented to him.An array $$$a$$$ of length $$$n$$$ is lexicographically smaller than an array $$$b$$$ of length $$$n$$$ if there is an index $$$i$$$ ($$$1 \le i \le n$$$) such that the first $$$i-1$$$ elements of arrays $$$a$$$ and $$$b$$$ are the same, and the $$$i$$$-th element of the array $$$a$$$ is less than the $$$i$$$-th element of the array $$$b$$$. For example, the array $$$a=[1, 3, 2, 3]$$$ is lexicographically smaller than the array $$$b=[1, 3, 4, 2]$$$.For example, if $$$n=7$$$ and $$$p=[3, 2, 4, 1, 7, 5, 6]$$$, then $$$q=[3, 3, 4, 4, 7, 7, 7]$$$ and the following permutations could have been as $$$p$$$ initially:   $$$[3, 1, 4, 2, 7, 5, 6]$$$ (lexicographically minimal permutation);  $$$[3, 1, 4, 2, 7, 6, 5]$$$;  $$$[3, 2, 4, 1, 7, 5, 6]$$$;  $$$[3, 2, 4, 1, 7, 6, 5]$$$ (lexicographically maximum permutation). For a given array $$$q$$$, find the lexicographically minimal and lexicographically maximal permutations that could have been originally presented to Polycarp.",[]166"Marin wants you to count number of permutations that are beautiful. A beautiful permutation of length $$$n$$$ is a permutation that has the following property: $$$$$$ \gcd (1 \cdot p_1, \, 2 \cdot p_2, \, \dots, \, n \cdot p_n) > 1, $$$$$$ where $$$\gcd$$$ is the greatest common divisor.A permutation is an array consisting of $$$n$$$ distinct integers from $$$1$$$ to $$$n$$$ in arbitrary order. For example, $$$[2,3,1,5,4]$$$ is a permutation, but $$$[1,2,2]$$$ is not a permutation ($$$2$$$ appears twice in the array) and $$$[1,3, 4]$$$ is also not a permutation ($$$n=3$$$ but there is $$$4$$$ in the array).","['math', 'number theory']"167"You are given a square matrix consisting of n rows and n columns. We assume that the rows are numbered from 1 to n from top to bottom and the columns are numbered from 1 to n from left to right. Some cells (n - 1 cells in total) of the the matrix are filled with ones, the remaining cells are filled with zeros. We can apply the following operations to the matrix:  Swap i-th and j-th rows of the matrix;  Swap i-th and j-th columns of the matrix. You are asked to transform the matrix into a special form using these operations. In that special form all the ones must be in the cells that lie below the main diagonal. Cell of the matrix, which is located on the intersection of the i-th row and of the j-th column, lies below the main diagonal if i > j.",['math']168"There are n points on a straight line, and the i-th point among them is located at xi. All these coordinates are distinct.Determine the number m — the smallest number of points you should add on the line to make the distances between all neighboring points equal. ",[]169"Jeff got 2n real numbers a1, a2, ..., a2n as a birthday present. The boy hates non-integer numbers, so he decided to slightly ""adjust"" the numbers he's got. Namely, Jeff consecutively executes n operations, each of them goes as follows:  choose indexes i and j (i ≠ j) that haven't been chosen yet;  round element ai to the nearest integer that isn't more than ai (assign to ai: ⌊ ai ⌋);  round element aj to the nearest integer that isn't less than aj (assign to aj: ⌈ aj ⌉). Nevertheless, Jeff doesn't want to hurt the feelings of the person who gave him the sequence. That's why the boy wants to perform the operations so as to make the absolute value of the difference between the sum of elements before performing the operations and the sum of elements after performing the operations as small as possible. Help Jeff find the minimum absolute value of the difference.",['math']170"You are given three strings $$$a$$$, $$$b$$$ and $$$c$$$ of the same length $$$n$$$. The strings consist of lowercase English letters only. The $$$i$$$-th letter of $$$a$$$ is $$$a_i$$$, the $$$i$$$-th letter of $$$b$$$ is $$$b_i$$$, the $$$i$$$-th letter of $$$c$$$ is $$$c_i$$$.For every $$$i$$$ ($$$1 \leq i \leq n$$$) you must swap (i.e. exchange) $$$c_i$$$ with either $$$a_i$$$ or $$$b_i$$$. So in total you'll perform exactly $$$n$$$ swap operations, each of them either $$$c_i \leftrightarrow a_i$$$ or $$$c_i \leftrightarrow b_i$$$ ($$$i$$$ iterates over all integers between $$$1$$$ and $$$n$$$, inclusive).For example, if $$$a$$$ is ""code"", $$$b$$$ is ""true"", and $$$c$$$ is ""help"", you can make $$$c$$$ equal to ""crue"" taking the $$$1$$$-st and the $$$4$$$-th letters from $$$a$$$ and the others from $$$b$$$. In this way $$$a$$$ becomes ""hodp"" and $$$b$$$ becomes ""tele"".Is it possible that after these swaps the string $$$a$$$ becomes exactly the same as the string $$$b$$$?",['strings']171"Ancient Egyptians are known to have understood difficult concepts in mathematics. The ancient Egyptian mathematician Ahmes liked to write a kind of arithmetic expressions on papyrus paper which he called as Ahmes arithmetic expression.An Ahmes arithmetic expression can be defined as:   ""d"" is an Ahmes arithmetic expression, where d is a one-digit positive integer;  ""(E1 op E2)"" is an Ahmes arithmetic expression, where E1 and E2 are valid Ahmes arithmetic expressions (without spaces) and op is either plus ( + ) or minus ( - ).  For example 5, (1-1) and ((1+(2-3))-5) are valid Ahmes arithmetic expressions.On his trip to Egypt, Fafa found a piece of papyrus paper having one of these Ahmes arithmetic expressions written on it. Being very ancient, the papyrus piece was very worn out. As a result, all the operators were erased, keeping only the numbers and the brackets. Since Fafa loves mathematics, he decided to challenge himself with the following task:Given the number of plus and minus operators in the original expression, find out the maximum possible value for the expression on the papyrus paper after putting the plus and minus operators in the place of the original erased operators.",['trees']172"Alice and Bob got very bored during a long car trip so they decided to play a game. From the window they can see cars of different colors running past them. Cars are going one after another.The game rules are like this. Firstly Alice chooses some color A, then Bob chooses some color B (A ≠ B). After each car they update the number of cars of their chosen color that have run past them. Let's define this numbers after i-th car cntA(i) and cntB(i).  If cntA(i) > cntB(i) for every i then the winner is Alice.  If cntB(i) ≥ cntA(i) for every i then the winner is Bob.  Otherwise it's a draw. Bob knows all the colors of cars that they will encounter and order of their appearance. Alice have already chosen her color A and Bob now wants to choose such color B that he will win the game (draw is not a win). Help him find this color.If there are multiple solutions, print any of them. If there is no such color then print -1.",[]173Almost every text editor has a built-in function of center text alignment. The developers of the popular in Berland text editor «Textpad» decided to introduce this functionality into the fourth release of the product.You are to implement the alignment in the shortest possible time. Good luck!,['strings']174"Let's define $$$p_i(n)$$$ as the following permutation: $$$[i, 1, 2, \dots, i - 1, i + 1, \dots, n]$$$. This means that the $$$i$$$-th permutation is almost identity (i.e. which maps every element to itself) permutation but the element $$$i$$$ is on the first position. Examples:  $$$p_1(4) = [1, 2, 3, 4]$$$;  $$$p_2(4) = [2, 1, 3, 4]$$$;  $$$p_3(4) = [3, 1, 2, 4]$$$;  $$$p_4(4) = [4, 1, 2, 3]$$$. You are given an array $$$x_1, x_2, \dots, x_m$$$ ($$$1 \le x_i \le n$$$).Let $$$pos(p, val)$$$ be the position of the element $$$val$$$ in $$$p$$$. So, $$$pos(p_1(4), 3) = 3, pos(p_2(4), 2) = 1, pos(p_4(4), 4) = 1$$$.Let's define a function $$$f(p) = \sum\limits_{i=1}^{m - 1} |pos(p, x_i) - pos(p, x_{i + 1})|$$$, where $$$|val|$$$ is the absolute value of $$$val$$$. This function means the sum of distances between adjacent elements of $$$x$$$ in $$$p$$$.Your task is to calculate $$$f(p_1(n)), f(p_2(n)), \dots, f(p_n(n))$$$.",['math']175"Jon Snow is on the lookout for some orbs required to defeat the white walkers. There are k different types of orbs and he needs at least one of each. One orb spawns daily at the base of a Weirwood tree north of the wall. The probability of this orb being of any kind is equal. As the north of wall is full of dangers, he wants to know the minimum number of days he should wait before sending a ranger to collect the orbs such that the probability of him getting at least one of each kind of orb is at least , where ε < 10 - 7.To better prepare himself, he wants to know the answer for q different values of pi. Since he is busy designing the battle strategy with Sam, he asks you for your help.","['math', 'probabilities']"176"You are given a permutation p of length n. Remove one element from permutation to make the number of records the maximum possible.We remind that in a sequence of numbers a1, a2, ..., ak the element ai is a record if for every integer j (1 ≤ j < i) the following holds: aj < ai. ",['math']177"Lee couldn't sleep lately, because he had nightmares. In one of his nightmares (which was about an unbalanced global round), he decided to fight back and propose a problem below (which you should solve) to balance the round, hopefully setting him free from the nightmares.A non-empty array $$$b_1, b_2, \ldots, b_m$$$ is called good, if there exist $$$m$$$ integer sequences which satisfy the following properties:  The $$$i$$$-th sequence consists of $$$b_i$$$ consecutive integers (for example if $$$b_i = 3$$$ then the $$$i$$$-th sequence can be $$$(-1, 0, 1)$$$ or $$$(-5, -4, -3)$$$ but not $$$(0, -1, 1)$$$ or $$$(1, 2, 3, 4)$$$).  Assuming the sum of integers in the $$$i$$$-th sequence is $$$sum_i$$$, we want $$$sum_1 + sum_2 + \ldots + sum_m$$$ to be equal to $$$0$$$. You are given an array $$$a_1, a_2, \ldots, a_n$$$. It has $$$2^n - 1$$$ nonempty subsequences. Find how many of them are good.As this number can be very large, output it modulo $$$10^9 + 7$$$.An array $$$c$$$ is a subsequence of an array $$$d$$$ if $$$c$$$ can be obtained from $$$d$$$ by deletion of several (possibly, zero or all) elements.","['math', 'number theory']"178"A permutation is an array consisting of $$$n$$$ distinct integers from $$$1$$$ to $$$n$$$ in arbitrary order. For example, $$$[2,3,1,5,4]$$$ is a permutation, but $$$[1,2,2]$$$ is not a permutation ($$$2$$$ appears twice in the array) and $$$[1,3,4]$$$ is also not a permutation ($$$n=3$$$ but there is $$$4$$$ in the array).You are given a permutation of $$$1,2,\dots,n$$$, $$$[a_1,a_2,\dots,a_n]$$$. For integers $$$i$$$, $$$j$$$ such that $$$1\le i<j\le n$$$, define $$$\operatorname{mn}(i,j)$$$ as $$$\min\limits_{k=i}^j a_k$$$, and define $$$\operatorname{mx}(i,j)$$$ as $$$\max\limits_{k=i}^j a_k$$$.Let us build an undirected graph of $$$n$$$ vertices, numbered $$$1$$$ to $$$n$$$. For every pair of integers $$$1\le i<j\le n$$$, if $$$\operatorname{mn}(i,j)=a_i$$$ and $$$\operatorname{mx}(i,j)=a_j$$$ both holds, or $$$\operatorname{mn}(i,j)=a_j$$$ and $$$\operatorname{mx}(i,j)=a_i$$$ both holds, add an undirected edge of length $$$1$$$ between vertices $$$i$$$ and $$$j$$$.In this graph, find the length of the shortest path from vertex $$$1$$$ to vertex $$$n$$$. We can prove that $$$1$$$ and $$$n$$$ will always be connected via some path, so a shortest path always exists.",[]179"ZS the Coder and Chris the Baboon are travelling to Udayland! To get there, they have to get on the special IOI bus. The IOI bus has n rows of seats. There are 4 seats in each row, and the seats are separated into pairs by a walkway. When ZS and Chris came, some places in the bus was already occupied.ZS and Chris are good friends. They insist to get a pair of neighbouring empty seats. Two seats are considered neighbouring if they are in the same row and in the same pair. Given the configuration of the bus, can you help ZS and Chris determine where they should sit?",[]180"The official capital and the cultural capital of Berland are connected by a single road running through n regions. Each region has a unique climate, so the i-th (1 ≤ i ≤ n) region has a stable temperature of ti degrees in summer.This summer a group of m schoolchildren wants to get from the official capital to the cultural capital to visit museums and sights. The trip organizers transport the children between the cities in buses, but sometimes it is very hot. Specifically, if the bus is driving through the i-th region and has k schoolchildren, then the temperature inside the bus is ti + k degrees.Of course, nobody likes it when the bus is hot. So, when the bus drives through the i-th region, if it has more than Ti degrees inside, each of the schoolchild in the bus demands compensation for the uncomfortable conditions. The compensation is as large as xi rubles and it is charged in each region where the temperature in the bus exceeds the limit.To save money, the organizers of the trip may arbitrarily add or remove extra buses in the beginning of the trip, and between regions (of course, they need at least one bus to pass any region). The organizers can also arbitrarily sort the children into buses, however, each of buses in the i-th region will cost the organizers costi rubles. Please note that sorting children into buses takes no money.Your task is to find the minimum number of rubles, which the organizers will have to spend to transport all schoolchildren.",[]181"There is a bus stop near the university. The lessons are over, and n students come to the stop. The i-th student will appear at the bus stop at time ti (all ti's are distinct).We shall assume that the stop is located on the coordinate axis Ox, at point x = 0, and the bus goes along the ray Ox, that is, towards the positive direction of the coordinate axis, and back. The i-th student needs to get to the point with coordinate xi (xi > 0).The bus moves by the following algorithm. Initially it is at point 0. The students consistently come to the stop and get on it. The bus has a seating capacity which is equal to m passengers. At the moment when m students get on the bus, it starts moving in the positive direction of the coordinate axis. Also it starts moving when the last (n-th) student gets on the bus. The bus is moving at a speed of 1 unit of distance per 1 unit of time, i.e. it covers distance y in time y.Every time the bus passes the point at which at least one student needs to get off, it stops and these students get off the bus. The students need 1 + [k / 2] units of time to get off the bus, where k is the number of students who leave at this point. Expression [k / 2] denotes rounded down k / 2. As soon as the last student leaves the bus, the bus turns around and goes back to the point x = 0. It doesn't make any stops until it reaches the point. At the given point the bus fills with students once more, and everything is repeated.If students come to the stop when there's no bus, they form a line (queue) and get on the bus in the order in which they came. Any number of students get on the bus in negligible time, you should assume that it doesn't take any time. Any other actions also take no time. The bus has no other passengers apart from the students.Write a program that will determine for each student the time when he got off the bus. The moment a student got off the bus is the moment the bus stopped at the student's destination stop (despite the fact that the group of students need some time to get off).",[]182"Let $$$\mathsf{AND}$$$ denote the bitwise AND operation, and $$$\mathsf{OR}$$$ denote the bitwise OR operation.You are given an array $$$a$$$ of length $$$n$$$ and a non-negative integer $$$k$$$. You can perform at most $$$k$$$ operations on the array of the following type:  Select an index $$$i$$$ ($$$1 \leq i \leq n$$$) and replace $$$a_i$$$ with $$$a_i$$$ $$$\mathsf{OR}$$$ $$$2^j$$$ where $$$j$$$ is any integer between $$$0$$$ and $$$30$$$ inclusive. In other words, in an operation you can choose an index $$$i$$$ ($$$1 \leq i \leq n$$$) and set the $$$j$$$-th bit of $$$a_i$$$ to $$$1$$$ ($$$0 \leq j \leq 30$$$). Output the maximum possible value of $$$a_1$$$ $$$\mathsf{AND}$$$ $$$a_2$$$ $$$\mathsf{AND}$$$ $$$\dots$$$ $$$\mathsf{AND}$$$ $$$a_n$$$ after performing at most $$$k$$$ operations. ",['math']183"A binary tree of $$$n$$$ nodes is given. Nodes of the tree are numbered from $$$1$$$ to $$$n$$$ and the root is the node $$$1$$$. Each node can have no child, only one left child, only one right child, or both children. For convenience, let's denote $$$l_u$$$ and $$$r_u$$$ as the left and the right child of the node $$$u$$$ respectively, $$$l_u = 0$$$ if $$$u$$$ does not have the left child, and $$$r_u = 0$$$ if the node $$$u$$$ does not have the right child.Each node has a string label, initially is a single character $$$c_u$$$. Let's define the string representation of the binary tree as the concatenation of the labels of the nodes in the in-order. Formally, let $$$f(u)$$$ be the string representation of the tree rooted at the node $$$u$$$. $$$f(u)$$$ is defined as follows: $$$$$$ f(u) = \begin{cases} \texttt{<empty string>}, & \text{if }u = 0; \\ f(l_u) + c_u + f(r_u) & \text{otherwise}, \end{cases} $$$$$$ where $$$+$$$ denotes the string concatenation operation.This way, the string representation of the tree is $$$f(1)$$$.For each node, we can duplicate its label at most once, that is, assign $$$c_u$$$ with $$$c_u + c_u$$$, but only if $$$u$$$ is the root of the tree, or if its parent also has its label duplicated.You are given the tree and an integer $$$k$$$. What is the lexicographically smallest string representation of the tree, if we can duplicate labels of at most $$$k$$$ nodes?A string $$$a$$$ is lexicographically smaller than a string $$$b$$$ if and only if one of the following holds:   $$$a$$$ is a prefix of $$$b$$$, but $$$a \ne b$$$;  in the first position where $$$a$$$ and $$$b$$$ differ, the string $$$a$$$ has a letter that appears earlier in the alphabet than the corresponding letter in $$$b$$$. ","['strings', 'trees']"184"Heidi and Doctor Who hopped out of the TARDIS and found themselves at EPFL in 2018. They were surrounded by stormtroopers and Darth Vader was approaching. Miraculously, they managed to escape to a nearby rebel base but the Doctor was very confused. Heidi reminded him that last year's HC2 theme was Star Wars. Now he understood, and he's ready to face the evils of the Empire!The rebels have $$$s$$$ spaceships, each with a certain attacking power $$$a$$$.They want to send their spaceships to destroy the empire bases and steal enough gold and supplies in order to keep the rebellion alive.The empire has $$$b$$$ bases, each with a certain defensive power $$$d$$$, and a certain amount of gold $$$g$$$.A spaceship can attack all the bases which have a defensive power less than or equal to its attacking power.If a spaceship attacks a base, it steals all the gold in that base.The rebels are still undecided which spaceship to send out first, so they asked for the Doctor's help. They would like to know, for each spaceship, the maximum amount of gold it can steal.",[]185"You are given a rebus of form ? + ? - ? + ? = n, consisting of only question marks, separated by arithmetic operation '+' and '-', equality and positive integer n. The goal is to replace each question mark with some positive integer from 1 to n, such that equality holds.",[]186"There are n pictures delivered for the new exhibition. The i-th painting has beauty ai. We know that a visitor becomes happy every time he passes from a painting to a more beautiful one.We are allowed to arranged pictures in any order. What is the maximum possible number of times the visitor may become happy while passing all pictures from first to last? In other words, we are allowed to rearrange elements of a in any order. What is the maximum possible number of indices i (1 ≤ i ≤ n - 1), such that ai + 1 > ai.",[]187"You are given a string $$$s$$$. You can build new string $$$p$$$ from $$$s$$$ using the following operation no more than two times:   choose any subsequence $$$s_{i_1}, s_{i_2}, \dots, s_{i_k}$$$ where $$$1 \le i_1 < i_2 < \dots < i_k \le |s|$$$;  erase the chosen subsequence from $$$s$$$ ($$$s$$$ can become empty);  concatenate chosen subsequence to the right of the string $$$p$$$ (in other words, $$$p = p + s_{i_1}s_{i_2}\dots s_{i_k}$$$). Of course, initially the string $$$p$$$ is empty. For example, let $$$s = \text{ababcd}$$$. At first, let's choose subsequence $$$s_1 s_4 s_5 = \text{abc}$$$ — we will get $$$s = \text{bad}$$$ and $$$p = \text{abc}$$$. At second, let's choose $$$s_1 s_2 = \text{ba}$$$ — we will get $$$s = \text{d}$$$ and $$$p = \text{abcba}$$$. So we can build $$$\text{abcba}$$$ from $$$\text{ababcd}$$$.Can you build a given string $$$t$$$ using the algorithm above?",['strings']188"Vasya has the sequence consisting of n integers. Vasya consider the pair of integers x and y k-interesting, if their binary representation differs from each other exactly in k bits. For example, if k = 2, the pair of integers x = 5 and y = 3 is k-interesting, because their binary representation x=101 and y=011 differs exactly in two bits.Vasya wants to know how many pairs of indexes (i, j) are in his sequence so that i < j and the pair of integers ai and aj is k-interesting. Your task is to help Vasya and determine this number.",[]189"The knight is standing in front of a long and narrow hallway. A princess is waiting at the end of it.In a hallway there are three doors: a red door, a green door and a blue door. The doors are placed one after another, however, possibly in a different order. To proceed to the next door, the knight must first open the door before.Each door can be only opened with a key of the corresponding color. So three keys: a red key, a green key and a blue key — are also placed somewhere in the hallway. To open the door, the knight should first pick up the key of its color.The knight has a map of the hallway. It can be transcribed as a string, consisting of six characters:   R, G, B — denoting red, green and blue doors, respectively;  r, g, b — denoting red, green and blue keys, respectively. Each of these six characters appears in the string exactly once.The knight is standing at the beginning of the hallway — on the left on the map.Given a map of the hallway, determine if the knight can open all doors and meet the princess at the end of the hallway.",[]190"You are given two integers $$$l$$$ and $$$r$$$, $$$l\le r$$$. Find the largest possible value of $$$a \bmod b$$$ over all pairs $$$(a, b)$$$ of integers for which $$$r\ge a \ge b \ge l$$$.As a reminder, $$$a \bmod b$$$ is a remainder we get when dividing $$$a$$$ by $$$b$$$. For example, $$$26 \bmod 8 = 2$$$.",['math']191"3R2 as DJ Mashiro - Happiness Breeze Ice - DJ Mashiro is dead or aliveNEKO#ΦωΦ has just got a new maze game on her PC!The game's main puzzle is a maze, in the forms of a $$$2 \times n$$$ rectangle grid. NEKO's task is to lead a Nekomimi girl from cell $$$(1, 1)$$$ to the gate at $$$(2, n)$$$ and escape the maze. The girl can only move between cells sharing a common side.However, at some moments during the game, some cells may change their state: either from normal ground to lava (which forbids movement into that cell), or vice versa (which makes that cell passable again). Initially all cells are of the ground type.After hours of streaming, NEKO finally figured out there are only $$$q$$$ such moments: the $$$i$$$-th moment toggles the state of cell $$$(r_i, c_i)$$$ (either from ground to lava or vice versa).Knowing this, NEKO wonders, after each of the $$$q$$$ moments, whether it is still possible to move from cell $$$(1, 1)$$$ to cell $$$(2, n)$$$ without going through any lava cells.Although NEKO is a great streamer and gamer, she still can't get through quizzes and problems requiring large amount of Brain Power. Can you help her?",[]192"The ship crashed into a reef and is sinking. Now the entire crew must be evacuated. All n crew members have already lined up in a row (for convenience let's label them all from left to right with positive integers from 1 to n) and await further instructions. However, one should evacuate the crew properly, in a strict order. Specifically:The first crew members to leave the ship are rats. Then women and children (both groups have the same priority) leave the ship. After that all men are evacuated from the ship. The captain leaves the sinking ship last.If we cannot determine exactly who should leave the ship first for any two members of the crew by the rules from the previous paragraph, then the one who stands to the left in the line leaves the ship first (or in other words, the one whose number in the line is less).For each crew member we know his status as a crew member, and also his name. All crew members have different names. Determine the order in which to evacuate the crew.",['strings']193"Guy-Manuel and Thomas are going to build a polygon spaceship. You're given a strictly convex (i. e. no three points are collinear) polygon $$$P$$$ which is defined by coordinates of its vertices. Define $$$P(x,y)$$$ as a polygon obtained by translating $$$P$$$ by vector $$$\overrightarrow {(x,y)}$$$. The picture below depicts an example of the translation:Define $$$T$$$ as a set of points which is the union of all $$$P(x,y)$$$ such that the origin $$$(0,0)$$$ lies in $$$P(x,y)$$$ (both strictly inside and on the boundary). There is also an equivalent definition: a point $$$(x,y)$$$ lies in $$$T$$$ only if there are two points $$$A,B$$$ in $$$P$$$ such that $$$\overrightarrow {AB} = \overrightarrow {(x,y)}$$$. One can prove $$$T$$$ is a polygon too. For example, if $$$P$$$ is a regular triangle then $$$T$$$ is a regular hexagon. At the picture below $$$P$$$ is drawn in black and some $$$P(x,y)$$$ which contain the origin are drawn in colored: The spaceship has the best aerodynamic performance if $$$P$$$ and $$$T$$$ are similar. Your task is to check whether the polygons $$$P$$$ and $$$T$$$ are similar.",['geometry']194"The only difference between easy and hard versions is that you should complete all the projects in easy version but this is not necessary in hard version.Polycarp is a very famous freelancer. His current rating is $$$r$$$ units.Some very rich customers asked him to complete some projects for their companies. To complete the $$$i$$$-th project, Polycarp needs to have at least $$$a_i$$$ units of rating; after he completes this project, his rating will change by $$$b_i$$$ (his rating will increase or decrease by $$$b_i$$$) ($$$b_i$$$ can be positive or negative). Polycarp's rating should not fall below zero because then people won't trust such a low rated freelancer.Is it possible to complete all the projects? Formally, write a program to check if such an order of the projects exists, that Polycarp has enough rating before starting each project, and he has non-negative rating after completing each project.In other words, you have to check that there exists such an order of projects in which Polycarp will complete them, so he has enough rating before starting each project, and has non-negative rating after completing each project.",[]195"In 2N - 1 boxes there are apples and oranges. Your task is to choose N boxes so, that they will contain not less than half of all the apples and not less than half of all the oranges.",[]196"You are playing a video game and you have just reached the bonus level, where the only possible goal is to score as many points as possible. Being a perfectionist, you've decided that you won't leave this level until you've gained the maximum possible number of points there.The bonus level consists of n small platforms placed in a line and numbered from 1 to n from left to right and (n - 1) bridges connecting adjacent platforms. The bridges between the platforms are very fragile, and for each bridge the number of times one can pass this bridge from one of its ends to the other before it collapses forever is known in advance.The player's actions are as follows. First, he selects one of the platforms to be the starting position for his hero. After that the player can freely move the hero across the platforms moving by the undestroyed bridges. As soon as the hero finds himself on a platform with no undestroyed bridge attached to it, the level is automatically ended. The number of points scored by the player at the end of the level is calculated as the number of transitions made by the hero between the platforms. Note that if the hero started moving by a certain bridge, he has to continue moving in the same direction until he is on a platform.Find how many points you need to score to be sure that nobody will beat your record, and move to the next level with a quiet heart.",[]197"Polycarpus has n friends in Tarasov city. Polycarpus knows phone numbers of all his friends: they are strings s1, s2, ..., sn. All these strings consist only of digits and have the same length. Once Polycarpus needed to figure out Tarasov city phone code. He assumed that the phone code of the city is the longest common prefix of all phone numbers of his friends. In other words, it is the longest string c which is a prefix (the beginning) of each si for all i (1 ≤ i ≤ n). Help Polycarpus determine the length of the city phone code. ",[]198"You are given $$$n$$$ strings $$$s_1, s_2, \dots, s_n$$$ of length at most $$$\mathbf{8}$$$. For each string $$$s_i$$$, determine if there exist two strings $$$s_j$$$ and $$$s_k$$$ such that $$$s_i = s_j + s_k$$$. That is, $$$s_i$$$ is the concatenation of $$$s_j$$$ and $$$s_k$$$. Note that $$$j$$$ can be equal to $$$k$$$.Recall that the concatenation of strings $$$s$$$ and $$$t$$$ is $$$s + t = s_1 s_2 \dots s_p t_1 t_2 \dots t_q$$$, where $$$p$$$ and $$$q$$$ are the lengths of strings $$$s$$$ and $$$t$$$ respectively. For example, concatenation of ""code"" and ""forces"" is ""codeforces"".",['strings']199"In some country there are exactly n cities and m bidirectional roads connecting the cities. Cities are numbered with integers from 1 to n. If cities a and b are connected by a road, then in an hour you can go along this road either from city a to city b, or from city b to city a. The road network is such that from any city you can get to any other one by moving along the roads.You want to destroy the largest possible number of roads in the country so that the remaining roads would allow you to get from city s1 to city t1 in at most l1 hours and get from city s2 to city t2 in at most l2 hours.Determine what maximum number of roads you need to destroy in order to meet the condition of your plan. If it is impossible to reach the desired result, print -1.",['graphs']200"Gildong has bought a famous painting software cfpaint. The working screen of cfpaint is square-shaped consisting of $$$n$$$ rows and $$$n$$$ columns of square cells. The rows are numbered from $$$1$$$ to $$$n$$$, from top to bottom, and the columns are numbered from $$$1$$$ to $$$n$$$, from left to right. The position of a cell at row $$$r$$$ and column $$$c$$$ is represented as $$$(r, c)$$$. There are only two colors for the cells in cfpaint — black and white.There is a tool named eraser in cfpaint. The eraser has an integer size $$$k$$$ ($$$1 \le k \le n$$$). To use the eraser, Gildong needs to click on a cell $$$(i, j)$$$ where $$$1 \le i, j \le n - k + 1$$$. When a cell $$$(i, j)$$$ is clicked, all of the cells $$$(i', j')$$$ where $$$i \le i' \le i + k - 1$$$ and $$$j \le j' \le j + k - 1$$$ become white. In other words, a square with side equal to $$$k$$$ cells and top left corner at $$$(i, j)$$$ is colored white.A white line is a row or a column without any black cells.Gildong has worked with cfpaint for some time, so some of the cells (possibly zero or all) are currently black. He wants to know the maximum number of white lines after using the eraser exactly once. Help Gildong find the answer to his question.",[]201"Note that the only difference between the easy and hard version is the constraint on the number of queries. You can make hacks only if all versions of the problem are solved.This is an interactive problem.You are given a tree consisting of $$$n$$$ nodes numbered with integers from $$$1$$$ to $$$n$$$. Ayush and Ashish chose two secret distinct nodes in the tree. You need to find out both the nodes. You can make the following query:   Provide a list of nodes and you will receive a node from that list whose sum of distances to both the hidden nodes is minimal (if there are multiple such nodes in the list, you will receive any one of them). You will also get the sum of distances of that node to the hidden nodes. Recall that a tree is a connected graph without cycles. The distance between two nodes is defined as the number of edges in the simple path between them.More formally, let's define two hidden nodes as $$$s$$$ and $$$f$$$. In one query you can provide the set of nodes $$$\{a_1, a_2, \ldots, a_c\}$$$ of the tree. As a result, you will get two numbers $$$a_i$$$ and $$$dist(a_i, s) + dist(a_i, f)$$$. The node $$$a_i$$$ is any node from the provided set, for which the number $$$dist(a_i, s) + dist(a_i, f)$$$ is minimal.You can ask no more than $$$11$$$ queries.","['graphs', 'trees']"202"Monocarp is playing Minecraft and wants to build a wall of cacti. He wants to build it on a field of sand of the size of $$$n \times m$$$ cells. Initially, there are cacti in some cells of the field. Note that, in Minecraft, cacti cannot grow on cells adjacent to each other by side — and the initial field meets this restriction. Monocarp can plant new cacti (they must also fulfil the aforementioned condition). He can't chop down any of the cacti that are already growing on the field — he doesn't have an axe, and the cacti are too prickly for his hands.Monocarp believes that the wall is complete if there is no path from the top row of the field to the bottom row, such that:   each two consecutive cells in the path are adjacent by side;  no cell belonging to the path contains a cactus. Your task is to plant the minimum number of cacti to build a wall (or to report that this is impossible).",['graphs']203"Recently Vasya learned that, given two points with different $$$x$$$ coordinates, you can draw through them exactly one parabola with equation of type $$$y = x^2 + bx + c$$$, where $$$b$$$ and $$$c$$$ are reals. Let's call such a parabola an $$$U$$$-shaped one.Vasya drew several distinct points with integer coordinates on a plane and then drew an $$$U$$$-shaped parabola through each pair of the points that have different $$$x$$$ coordinates. The picture became somewhat messy, but Vasya still wants to count how many of the parabolas drawn don't have any drawn point inside their internal area. Help Vasya.The internal area of an $$$U$$$-shaped parabola is the part of the plane that lies strictly above the parabola when the $$$y$$$ axis is directed upwards.","['math', 'geometry']"204"A picture can be represented as an $$$n\times m$$$ grid ($$$n$$$ rows and $$$m$$$ columns) so that each of the $$$n \cdot m$$$ cells is colored with one color. You have $$$k$$$ pigments of different colors. You have a limited amount of each pigment, more precisely you can color at most $$$a_i$$$ cells with the $$$i$$$-th pigment.A picture is considered beautiful if each cell has at least $$$3$$$ toroidal neighbors with the same color as itself.Two cells are considered toroidal neighbors if they toroidally share an edge. In other words, for some integers $$$1 \leq x_1,x_2 \leq n$$$ and $$$1 \leq y_1,y_2 \leq m$$$, the cell in the $$$x_1$$$-th row and $$$y_1$$$-th column is a toroidal neighbor of the cell in the $$$x_2$$$-th row and $$$y_2$$$-th column if one of following two conditions holds:  $$$x_1-x_2 \equiv \pm1 \pmod{n}$$$ and $$$y_1=y_2$$$, or  $$$y_1-y_2 \equiv \pm1 \pmod{m}$$$ and $$$x_1=x_2$$$. Notice that each cell has exactly $$$4$$$ toroidal neighbors. For example, if $$$n=3$$$ and $$$m=4$$$, the toroidal neighbors of the cell $$$(1, 2)$$$ (the cell on the first row and second column) are: $$$(3, 2)$$$, $$$(2, 2)$$$, $$$(1, 3)$$$, $$$(1, 1)$$$. They are shown in gray on the image below:  The gray cells show toroidal neighbors of $$$(1, 2)$$$. Is it possible to color all cells with the pigments provided and create a beautiful picture?",[]205"Polygon is not only the best platform for developing problems but also a square matrix with side $$$n$$$, initially filled with the character 0.On the polygon, military training was held. The soldiers placed a cannon above each cell in the first row and a cannon to the left of each cell in the first column. Thus, exactly $$$2n$$$ cannons were placed.    Initial polygon for $$$n=4$$$. Cannons shoot character 1. At any moment of time, no more than one cannon is shooting. When a 1 flies out of a cannon, it flies forward (in the direction of the shot) until it collides with a polygon border or another 1. After that, it takes the cell in which it was before the collision and remains there. Take a look at the examples for better understanding.More formally:   if a cannon stands in the row $$$i$$$, to the left of the first column, and shoots with a 1, then the 1 starts its flight from the cell ($$$i, 1$$$) and ends in some cell ($$$i, j$$$);  if a cannon stands in the column $$$j$$$, above the first row, and shoots with a 1, then the 1 starts its flight from the cell ($$$1, j$$$) and ends in some cell ($$$i, j$$$). For example, consider the following sequence of shots:   1. Shoot the cannon in the row $$$2$$$.                         2. Shoot the cannon in the row $$$2$$$.                         3. Shoot the cannon in column $$$3$$$. You have a report from the military training on your desk. This report is a square matrix with side length $$$n$$$ consisting of 0 and 1. You wonder if the training actually happened. In other words, is there a sequence of shots such that, after the training, you get the given matrix?Each cannon can make an arbitrary number of shots. Before the training, each cell of the polygon contains 0.",['graphs']206"Petya organized a strange birthday party. He invited $$$n$$$ friends and assigned an integer $$$k_i$$$ to the $$$i$$$-th of them. Now Petya would like to give a present to each of them. In the nearby shop there are $$$m$$$ unique presents available, the $$$j$$$-th present costs $$$c_j$$$ dollars ($$$1 \le c_1 \le c_2 \le \ldots \le c_m$$$). It's not allowed to buy a single present more than once.For the $$$i$$$-th friend Petya can either buy them a present $$$j \le k_i$$$, which costs $$$c_j$$$ dollars, or just give them $$$c_{k_i}$$$ dollars directly.Help Petya determine the minimum total cost of hosting his party.",[]207"Berland annual chess tournament is coming!Organizers have gathered 2·n chess players who should be divided into two teams with n people each. The first team is sponsored by BerOil and the second team is sponsored by BerMobile. Obviously, organizers should guarantee the win for the team of BerOil.Thus, organizers should divide all 2·n players into two teams with n people each in such a way that the first team always wins.Every chess player has its rating ri. It is known that chess player with the greater rating always wins the player with the lower rating. If their ratings are equal then any of the players can win.After teams assignment there will come a drawing to form n pairs of opponents: in each pair there is a player from the first team and a player from the second team. Every chess player should be in exactly one pair. Every pair plays once. The drawing is totally random.Is it possible to divide all 2·n players into two teams with n people each so that the player from the first team in every pair wins regardless of the results of the drawing?",[]208"You are given a binary matrix $$$a$$$ of size $$$n \times m$$$. A binary matrix is a matrix where each element is either $$$0$$$ or $$$1$$$.You may perform some (possibly zero) operations with this matrix. During each operation you can inverse the row of this matrix or a column of this matrix. Formally, inverting a row is changing all values in this row to the opposite ($$$0$$$ to $$$1$$$, $$$1$$$ to $$$0$$$). Inverting a column is changing all values in this column to the opposite.Your task is to sort the initial matrix by some sequence of such operations. The matrix is considered sorted if the array $$$[a_{1, 1}, a_{1, 2}, \dots, a_{1, m}, a_{2, 1}, a_{2, 2}, \dots, a_{2, m}, \dots, a_{n, m - 1}, a_{n, m}]$$$ is sorted in non-descending order.",[]209"Anton came to a chocolate factory. There he found a working conveyor and decided to run on it from the beginning to the end.The conveyor is a looped belt with a total length of 2l meters, of which l meters are located on the surface and are arranged in a straight line. The part of the belt which turns at any moment (the part which emerges from under the floor to the surface and returns from the surface under the floor) is assumed to be negligibly short.The belt is moving uniformly at speed v1 meters per second. Anton will be moving on it in the same direction at the constant speed of v2 meters per second, so his speed relatively to the floor will be v1 + v2 meters per second. Anton will neither stop nor change the speed or the direction of movement.Here and there there are chocolates stuck to the belt (n chocolates). They move together with the belt, and do not come off it. Anton is keen on the chocolates, but he is more keen to move forward. So he will pick up all the chocolates he will pass by, but nothing more. If a chocolate is at the beginning of the belt at the moment when Anton starts running, he will take it, and if a chocolate is at the end of the belt at the moment when Anton comes off the belt, he will leave it.     The figure shows an example with two chocolates. One is located   in the position a1 = l - d, and is now on the top half of the belt, the second one   is in the position a2 = 2l - d, and is now on the bottom half of the belt.  You are given the positions of the chocolates relative to the initial start position of the belt 0 ≤ a1 < a2 < ... < an < 2l. The positions on the belt from 0 to l correspond to the top, and from l to 2l — to the the bottom half of the belt (see example). All coordinates are given in meters.Anton begins to run along the belt at a random moment of time. This means that all possible positions of the belt at the moment he starts running are equiprobable. For each i from 0 to n calculate the probability that Anton will pick up exactly i chocolates.",[]210"Three swimmers decided to organize a party in the swimming pool! At noon, they started to swim from the left side of the pool.It takes the first swimmer exactly $$$a$$$ minutes to swim across the entire pool and come back, exactly $$$b$$$ minutes for the second swimmer and $$$c$$$ minutes for the third. Hence, the first swimmer will be on the left side of the pool after $$$0$$$, $$$a$$$, $$$2a$$$, $$$3a$$$, ... minutes after the start time, the second one will be at $$$0$$$, $$$b$$$, $$$2b$$$, $$$3b$$$, ... minutes, and the third one will be on the left side of the pool after $$$0$$$, $$$c$$$, $$$2c$$$, $$$3c$$$, ... minutes.You came to the left side of the pool exactly $$$p$$$ minutes after they started swimming. Determine how long you have to wait before one of the swimmers arrives at the left side of the pool.",['math']211"Word $$$s$$$ of length $$$n$$$ is called $$$k$$$-complete if   $$$s$$$ is a palindrome, i.e. $$$s_i=s_{n+1-i}$$$ for all $$$1 \le i \le n$$$;  $$$s$$$ has a period of $$$k$$$, i.e. $$$s_i=s_{k+i}$$$ for all $$$1 \le i \le n-k$$$. For example, ""abaaba"" is a $$$3$$$-complete word, while ""abccba"" is not.Bob is given a word $$$s$$$ of length $$$n$$$ consisting of only lowercase Latin letters and an integer $$$k$$$, such that $$$n$$$ is divisible by $$$k$$$. He wants to convert $$$s$$$ to any $$$k$$$-complete word.To do this Bob can choose some $$$i$$$ ($$$1 \le i \le n$$$) and replace the letter at position $$$i$$$ with some other lowercase Latin letter.So now Bob wants to know the minimum number of letters he has to replace to convert $$$s$$$ to any $$$k$$$-complete word.Note that Bob can do zero changes if the word $$$s$$$ is already $$$k$$$-complete.You are required to answer $$$t$$$ test cases independently.",['strings']212"Allen is hosting a formal dinner party. $$$2n$$$ people come to the event in $$$n$$$ pairs (couples). After a night of fun, Allen wants to line everyone up for a final picture. The $$$2n$$$ people line up, but Allen doesn't like the ordering. Allen prefers if each pair occupies adjacent positions in the line, as this makes the picture more aesthetic.Help Allen find the minimum number of swaps of adjacent positions he must perform to make it so that each couple occupies adjacent positions in the line.",['math']213" Denis, after buying flowers and sweets (you will learn about this story in the next task), went to a date with Nastya to ask her to become a couple. Now, they are sitting in the cafe and finally... Denis asks her to be together, but ... Nastya doesn't give any answer. The poor boy was very upset because of that. He was so sad that he punched some kind of scoreboard with numbers. The numbers are displayed in the same way as on an electronic clock: each digit position consists of $$$7$$$ segments, which can be turned on or off to display different numbers. The picture shows how all $$$10$$$ decimal digits are displayed:   After the punch, some segments stopped working, that is, some segments might stop glowing if they glowed earlier. But Denis remembered how many sticks were glowing and how many are glowing now. Denis broke exactly $$$k$$$ segments and he knows which sticks are working now. Denis came up with the question: what is the maximum possible number that can appear on the board if you turn on exactly $$$k$$$ sticks (which are off now)? It is allowed that the number includes leading zeros.",[]214"For an array $$$a$$$ of integers let's denote its maximal element as $$$\max(a)$$$, and minimal as $$$\min(a)$$$. We will call an array $$$a$$$ of $$$k$$$ integers interesting if $$$\max(a) - \min(a) \ge k$$$. For example, array $$$[1, 3, 4, 3]$$$ isn't interesting as $$$\max(a) - \min(a) = 4 - 1 = 3 < 4$$$ while array $$$[7, 3, 0, 4, 3]$$$ is as $$$\max(a) - \min(a) = 7 - 0 = 7 \ge 5$$$.You are given an array $$$a$$$ of $$$n$$$ integers. Find some interesting nonempty subarray of $$$a$$$, or tell that it doesn't exist.An array $$$b$$$ is a subarray of an array $$$a$$$ if $$$b$$$ can be obtained from $$$a$$$ by deletion of several (possibly, zero or all) elements from the beginning and several (possibly, zero or all) elements from the end. In particular, an array is a subarray of itself.",['math']215"The government of Berland decided to improve network coverage in his country. Berland has a unique structure: the capital in the center and $$$n$$$ cities in a circle around the capital. The capital already has a good network coverage (so the government ignores it), but the $$$i$$$-th city contains $$$a_i$$$ households that require a connection.The government designed a plan to build $$$n$$$ network stations between all pairs of neighboring cities which will maintain connections only for these cities. In other words, the $$$i$$$-th network station will provide service only for the $$$i$$$-th and the $$$(i + 1)$$$-th city (the $$$n$$$-th station is connected to the $$$n$$$-th and the $$$1$$$-st city).All network stations have capacities: the $$$i$$$-th station can provide the connection to at most $$$b_i$$$ households.Now the government asks you to check can the designed stations meet the needs of all cities or not — that is, is it possible to assign each household a network station so that each network station $$$i$$$ provides the connection to at most $$$b_i$$$ households.",[]216"Oleg the bank client and Igor the analyst are arguing again. This time, they want to pick a gift as a present for their friend, ZS the coder. After a long thought, they decided that their friend loves to eat carrots the most and thus they want to pick the best carrot as their present.There are n carrots arranged in a line. The i-th carrot from the left has juiciness ai. Oleg thinks ZS loves juicy carrots whereas Igor thinks that he hates juicy carrots. Thus, Oleg would like to maximize the juiciness of the carrot they choose while Igor would like to minimize the juiciness of the carrot they choose.To settle this issue, they decided to play a game again. Oleg and Igor take turns to play the game. In each turn, a player can choose a carrot from either end of the line, and eat it. The game ends when only one carrot remains. Oleg moves first. The last remaining carrot will be the carrot that they will give their friend, ZS.Oleg is a sneaky bank client. When Igor goes to a restroom, he performs k moves before the start of the game. Each move is the same as above (eat a carrot from either end of the line). After Igor returns, they start the game with Oleg still going first. Oleg wonders: for each k such that 0 ≤ k ≤ n - 1, what is the juiciness of the carrot they will give to ZS if he makes k extra moves beforehand and both players play optimally?","['math', 'games']"217"This is an interactive problem. Remember to flush your output while communicating with the testing program. You may use fflush(stdout) in C++, system.out.flush() in Java, stdout.flush() in Python or flush(output) in Pascal to flush the output. If you use some other programming language, consult its documentation. You may also refer to the guide on interactive problems: https://codeforces.com/blog/entry/45307.There is a city in which Dixit lives. In the city, there are $$$n$$$ houses. There is  exactly one directed road between every pair of houses. For example, consider two houses A and B, then there is a directed road either from A to B or from B to A but not both. The number of roads leading to the $$$i$$$-th house is $$$k_i$$$.Two houses A and B are bi-reachable if A is reachable from B and B is reachable from A. We say that house B is reachable from house A when there is a path from house A to house B.Dixit wants to buy two houses in the city, that is, one for living and one for studying. Of course, he would like to travel from one house to another. So, he wants to find a pair of bi-reachable houses A and B. Among all such pairs, he wants to choose one with the maximum value of $$$|k_A - k_B|$$$, where $$$k_i$$$ is the number of roads leading to the house $$$i$$$. If more than one optimal pair exists, any of them is suitable.Since Dixit is busy preparing CodeCraft, can you help him find the desired pair of houses, or tell him that no such houses exist?In the problem input, you are not given the direction of each road. You are given — for each house — only the number of incoming roads to that house ($$$k_i$$$).You are allowed to ask only one type of query from the judge: give two houses A and B, and the judge answers whether B is reachable from A. There is no upper limit on the number of queries. But, you cannot ask more queries after the judge answers ""Yes"" to any of your queries. Also, you cannot ask the same query twice.Once you have exhausted all your queries (or the judge responds ""Yes"" to any of your queries), your program must output its guess for the two houses and quit.See the Interaction section below for more details.",['graphs']218"When Valera has got some free time, he goes to the library to read some books. Today he's got t free minutes to read. That's why Valera took n books in the library and for each book he estimated the time he is going to need to read it. Let's number the books by integers from 1 to n. Valera needs ai minutes to read the i-th book.Valera decided to choose an arbitrary book with number i and read the books one by one, starting from this book. In other words, he will first read book number i, then book number i + 1, then book number i + 2 and so on. He continues the process until he either runs out of the free time or finishes reading the n-th book. Valera reads each book up to the end, that is, he doesn't start reading the book if he doesn't have enough free time to finish reading it. Print the maximum number of books Valera can read.",[]219"You are given an integer $$$n$$$ and an array $$$a_1,a_2,\ldots,a_n$$$.In one operation, you can choose an index $$$i$$$ ($$$1 \le i \lt n$$$) for which $$$a_i \neq a_{i+1}$$$ and delete both $$$a_i$$$ and $$$a_{i+1}$$$ from the array. After deleting $$$a_i$$$ and $$$a_{i+1}$$$, the remaining parts of the array are concatenated.For example, if $$$a=[1,4,3,3,6,2]$$$, then after performing an operation with $$$i=2$$$, the resulting array will be $$$[1,3,6,2]$$$.What is the maximum possible length of an array of equal elements obtainable from $$$a$$$ by performing several (perhaps none) of the aforementioned operations?",[]220"You are given a string A. Find a string B, where B is a palindrome and A is a subsequence of B.A subsequence of a string is a string that can be derived from it by deleting some (not necessarily consecutive) characters without changing the order of the remaining characters. For example, ""cotst"" is a subsequence of ""contest"".A palindrome is a string that reads the same forward or backward.The length of string B should be at most 104. It is guaranteed that there always exists such string.You do not need to find the shortest answer, the only restriction is that the length of string B should not exceed 104.",[]221"Kevin has just recevied his disappointing results on the USA Identification of Cows Olympiad (USAICO) in the form of a binary string of length n. Each character of Kevin's string represents Kevin's score on one of the n questions of the olympiad—'1' for a correctly identified cow and '0' otherwise.However, all is not lost. Kevin is a big proponent of alternative thinking and believes that his score, instead of being the sum of his points, should be the length of the longest alternating subsequence of his string. Here, we define an alternating subsequence of a string as a not-necessarily contiguous subsequence where no two consecutive elements are equal. For example, {0, 1, 0, 1}, {1, 0, 1}, and {1, 0, 1, 0} are alternating sequences, while {1, 0, 0} and {0, 1, 0, 1, 1} are not.Kevin, being the sneaky little puffball that he is, is willing to hack into the USAICO databases to improve his score. In order to be subtle, he decides that he will flip exactly one substring—that is, take a contiguous non-empty substring of his score and change all '0's in that substring to '1's and vice versa. After such an operation, Kevin wants to know the length of the longest possible alternating subsequence that his string could have.",['math']222"Many years ago Berland was a small country where only $$$n$$$ people lived. Each person had some savings: the $$$i$$$-th one had $$$a_i$$$ burles.The government considered a person as wealthy if he had at least $$$x$$$ burles. To increase the number of wealthy people Berland decided to carry out several reforms. Each reform looked like that:   the government chooses some subset of people (maybe all of them);  the government takes all savings from the chosen people and redistributes the savings among the chosen people equally. For example, consider the savings as list $$$[5, 1, 2, 1]$$$: if the government chose the $$$1$$$-st and the $$$3$$$-rd persons then it, at first, will take all $$$5 + 2 = 7$$$ burles and after that will return $$$3.5$$$ burles to the chosen people. As a result, the savings will become $$$[3.5, 1, 3.5, 1]$$$.A lot of data was lost from that time, so we don't know how many reforms were implemented and to whom. All we can do is ask you to calculate the maximum possible number of wealthy people after several (maybe zero) reforms.",[]223"This is the easier version of the problem. In this version, $$$1 \le n \le 10^5$$$ and $$$0 \le a_i \le 1$$$. You can hack this problem only if you solve and lock both problems.Christmas is coming, and our protagonist, Bob, is preparing a spectacular present for his long-time best friend Alice. This year, he decides to prepare $$$n$$$ boxes of chocolate, numbered from $$$1$$$ to $$$n$$$. Initially, the $$$i$$$-th box contains $$$a_i$$$ chocolate pieces.Since Bob is a typical nice guy, he will not send Alice $$$n$$$ empty boxes. In other words, at least one of $$$a_1, a_2, \ldots, a_n$$$ is positive. Since Alice dislikes coprime sets, she will be happy only if there exists some integer $$$k > 1$$$ such that the number of pieces in each box is divisible by $$$k$$$. Note that Alice won't mind if there exists some empty boxes. Charlie, Alice's boyfriend, also is Bob's second best friend, so he decides to help Bob by rearranging the chocolate pieces. In one second, Charlie can pick up a piece in box $$$i$$$ and put it into either box $$$i-1$$$ or box $$$i+1$$$ (if such boxes exist). Of course, he wants to help his friend as quickly as possible. Therefore, he asks you to calculate the minimum number of seconds he would need to make Alice happy.","['math', 'number theory']"224"Paw the Spider is making a web. Web-making is a real art, Paw has been learning to do it his whole life. Let's consider the structure of the web.  There are n main threads going from the center of the web. All main threads are located in one plane and divide it into n equal infinite sectors. The sectors are indexed from 1 to n in the clockwise direction. Sectors i and i + 1 are adjacent for every i, 1 ≤ i < n. In addition, sectors 1 and n are also adjacent.Some sectors have bridge threads. Each bridge connects the two main threads that make up this sector. The points at which the bridge is attached to the main threads will be called attachment points. Both attachment points of a bridge are at the same distance from the center of the web. At each attachment point exactly one bridge is attached. The bridges are adjacent if they are in the same sector, and there are no other bridges between them.A cell of the web is a trapezoid, which is located in one of the sectors and is bounded by two main threads and two adjacent bridges. You can see that the sides of the cell may have the attachment points of bridges from adjacent sectors. If the number of attachment points on one side of the cell is not equal to the number of attachment points on the other side, it creates an imbalance of pulling forces on this cell and this may eventually destroy the entire web. We'll call such a cell unstable. The perfect web does not contain unstable cells.Unstable cells are marked red in the figure. Stable cells are marked green.Paw the Spider isn't a skillful webmaker yet, he is only learning to make perfect webs. Help Paw to determine the number of unstable cells in the web he has just spun.",[]225"Consider an infinite triangle made up of layers. Let's number the layers, starting from one, from the top of the triangle (from top to bottom). The $$$k$$$-th layer of the triangle contains $$$k$$$ points, numbered from left to right. Each point of an infinite triangle is described by a pair of numbers $$$(r, c)$$$ ($$$1 \le c \le r$$$), where $$$r$$$ is the number of the layer, and $$$c$$$ is the number of the point in the layer. From each point $$$(r, c)$$$ there are two directed edges to the points $$$(r+1, c)$$$ and $$$(r+1, c+1)$$$, but only one of the edges is activated. If $$$r + c$$$ is even, then the edge to the point $$$(r+1, c)$$$ is activated, otherwise the edge to the point $$$(r+1, c+1)$$$ is activated. Look at the picture for a better understanding.  Activated edges are colored in black. Non-activated edges are colored in gray. From the point $$$(r_1, c_1)$$$ it is possible to reach the point $$$(r_2, c_2)$$$, if there is a path between them only from activated edges. For example, in the picture above, there is a path from $$$(1, 1)$$$ to $$$(3, 2)$$$, but there is no path from $$$(2, 1)$$$ to $$$(1, 1)$$$.Initially, you are at the point $$$(1, 1)$$$. For each turn, you can:   Replace activated edge for point $$$(r, c)$$$. That is if the edge to the point $$$(r+1, c)$$$ is activated, then instead of it, the edge to the point $$$(r+1, c+1)$$$ becomes activated, otherwise if the edge to the point $$$(r+1, c+1)$$$, then instead if it, the edge to the point $$$(r+1, c)$$$ becomes activated. This action increases the cost of the path by $$$1$$$;  Move from the current point to another by following the activated edge. This action does not increase the cost of the path. You are given a sequence of $$$n$$$ points of an infinite triangle $$$(r_1, c_1), (r_2, c_2), \ldots, (r_n, c_n)$$$. Find the minimum cost path from $$$(1, 1)$$$, passing through all $$$n$$$ points in arbitrary order.","['math', 'graphs']"226"There are $$$n$$$ beautiful skyscrapers in New York, the height of the $$$i$$$-th one is $$$h_i$$$. Today some villains have set on fire first $$$n - 1$$$ of them, and now the only safety building is $$$n$$$-th skyscraper.Let's call a jump from $$$i$$$-th skyscraper to $$$j$$$-th ($$$i < j$$$) discrete, if all skyscrapers between are strictly lower or higher than both of them. Formally, jump is discrete, if $$$i < j$$$ and one of the following conditions satisfied:   $$$i + 1 = j$$$  $$$\max(h_{i + 1}, \ldots, h_{j - 1}) < \min(h_i, h_j)$$$  $$$\max(h_i, h_j) < \min(h_{i + 1}, \ldots, h_{j - 1})$$$. At the moment, Vasya is staying on the first skyscraper and wants to live a little longer, so his goal is to reach $$$n$$$-th skyscraper with minimal count of discrete jumps. Help him with calcualting this number.",['graphs']227"There are $$$n$$$ cities and $$$m$$$ bidirectional roads in the country. The roads in the country form an undirected weighted graph. The graph is not guaranteed to be connected. Each road has it's own parameter $$$w$$$. You can travel through the roads, but the government made a new law: you can only go through two roads at a time (go from city $$$a$$$ to city $$$b$$$ and then from city $$$b$$$ to city $$$c$$$) and you will have to pay $$$(w_{ab} + w_{bc})^2$$$ money to go through those roads. Find out whether it is possible to travel from city $$$1$$$ to every other city $$$t$$$ and what's the minimum amount of money you need to get from $$$1$$$ to $$$t$$$.",['graphs']228"A function  is called Lipschitz continuous if there is a real constant K such that the inequality |f(x) - f(y)| ≤ K·|x - y| holds for all . We'll deal with a more... discrete version of this term.For an array , we define it's Lipschitz constant  as follows:  if n < 2,   if n ≥ 2,  over all 1 ≤ i < j ≤ n In other words,  is the smallest non-negative integer such that |h[i] - h[j]| ≤ L·|i - j| holds for all 1 ≤ i, j ≤ n.You are given an array  of size n and q queries of the form [l, r]. For each query, consider the subarray ; determine the sum of Lipschitz constants of all subarrays of .",['math']229"$$$n$$$ players are playing a game. There are two different maps in the game. For each player, we know his strength on each map. When two players fight on a specific map, the player with higher strength on that map always wins. No two players have the same strength on the same map. You are the game master and want to organize a tournament. There will be a total of $$$n-1$$$ battles. While there is more than one player in the tournament, choose any map and any two remaining players to fight on it. The player who loses will be eliminated from the tournament. In the end, exactly one player will remain, and he is declared the winner of the tournament. For each player determine if he can win the tournament.",['graphs']230You are given array a with n elements and the number m. Consider some subsequence of a and the value of least common multiple (LCM) of its elements. Denote LCM as l. Find any longest subsequence of a with the value l ≤ m.A subsequence of a is an array we can get by erasing some elements of a. It is allowed to erase zero or all elements.The LCM of an empty array equals 1.,"['math', 'number theory']"231"Let's introduce the designation , where x is a string, n is a positive integer and operation "" + "" is the string concatenation operation. For example, [abc, 2] = abcabc.We'll say that string s can be obtained from string t, if we can remove some characters from string t and obtain string s. For example, strings ab and aсba can be obtained from string xacbac, and strings bx and aaa cannot be obtained from it.Sereja has two strings, w = [a, b] and q = [c, d]. He wants to find such maximum integer p (p > 0), that [q, p] can be obtained from string w.",['strings']232"An array $$$b$$$ is called to be a subarray of $$$a$$$ if it forms a continuous subsequence of $$$a$$$, that is, if it is equal to $$$a_l$$$, $$$a_{l + 1}$$$, $$$\ldots$$$, $$$a_r$$$ for some $$$l, r$$$.Suppose $$$m$$$ is some known constant. For any array, having $$$m$$$ or more elements, let's define it's beauty as the sum of $$$m$$$ largest elements of that array. For example:   For array $$$x = [4, 3, 1, 5, 2]$$$ and $$$m = 3$$$, the $$$3$$$ largest elements of $$$x$$$ are $$$5$$$, $$$4$$$ and $$$3$$$, so the beauty of $$$x$$$ is $$$5 + 4 + 3 = 12$$$. For array $$$x = [10, 10, 10]$$$ and $$$m = 2$$$, the beauty of $$$x$$$ is $$$10 + 10 = 20$$$.You are given an array $$$a_1, a_2, \ldots, a_n$$$, the value of the said constant $$$m$$$ and an integer $$$k$$$. Your need to split the array $$$a$$$ into exactly $$$k$$$ subarrays such that:  Each element from $$$a$$$ belongs to exactly one subarray. Each subarray has at least $$$m$$$ elements. The sum of all beauties of $$$k$$$ subarrays is maximum possible.",[]233"You are playing a game similar to Sokoban on an infinite number line. The game is discrete, so you only consider integer positions on the line.You start on a position $$$0$$$. There are $$$n$$$ boxes, the $$$i$$$-th box is on a position $$$a_i$$$. All positions of the boxes are distinct. There are also $$$m$$$ special positions, the $$$j$$$-th position is $$$b_j$$$. All the special positions are also distinct.In one move you can go one position to the left or to the right. If there is a box in the direction of your move, then you push the box to the next position in that direction. If the next position is taken by another box, then that box is also pushed to the next position, and so on. You can't go through the boxes. You can't pull the boxes towards you.You are allowed to perform any number of moves (possibly, zero). Your goal is to place as many boxes on special positions as possible. Note that some boxes can be initially placed on special positions.",[]234"Andrew and Eugene are playing a game. Initially, Andrew has string s, consisting of digits. Eugene sends Andrew multiple queries of type ""di → ti"", that means ""replace all digits di in string s with substrings equal to ti"". For example, if s = 123123, then query ""2 → 00"" transforms s to 10031003, and query ""3 → "" (""replace 3 by an empty string"") transforms it to s = 1212. After all the queries Eugene asks Andrew to find the remainder after division of number with decimal representation equal to s by 1000000007 (109 + 7). When you represent s as a decimal number, please ignore the leading zeroes; also if s is an empty string, then it's assumed that the number equals to zero.Andrew got tired of processing Eugene's requests manually and he asked you to write a program for that. Help him!",[]235Let's call a permutation $$$p$$$ of length $$$n$$$ anti-Fibonacci if the condition $$$p_{i-2} + p_{i-1} \ne p_i$$$ holds for all $$$i$$$ ($$$3 \le i \le n$$$). Recall that the permutation is the array of length $$$n$$$ which contains each integer from $$$1$$$ to $$$n$$$ exactly once.Your task is for a given number $$$n$$$ print $$$n$$$ distinct anti-Fibonacci permutations of length $$$n$$$.,[]236"You are given an integer $$$n$$$ and an array $$$a_1, a_2, \ldots, a_n$$$. You should reorder the elements of the array $$$a$$$ in such way that the sum of $$$\textbf{MEX}$$$ on prefixes ($$$i$$$-th prefix is $$$a_1, a_2, \ldots, a_i$$$) is maximized.Formally, you should find an array $$$b_1, b_2, \ldots, b_n$$$, such that the sets of elements of arrays $$$a$$$ and $$$b$$$ are equal (it is equivalent to array $$$b$$$ can be found as an array $$$a$$$ with some reordering of its elements) and $$$\sum\limits_{i=1}^{n} \textbf{MEX}(b_1, b_2, \ldots, b_i)$$$ is maximized.$$$\textbf{MEX}$$$ of a set of nonnegative integers is the minimal nonnegative integer such that it is not in the set.For example, $$$\textbf{MEX}(\{1, 2, 3\}) = 0$$$, $$$\textbf{MEX}(\{0, 1, 2, 4, 5\}) = 3$$$.",[]237"Little Dima has two sequences of points with integer coordinates: sequence (a1, 1), (a2, 2), ..., (an, n) and sequence (b1, 1), (b2, 2), ..., (bn, n).Now Dima wants to count the number of distinct sequences of points of length 2·n that can be assembled from these sequences, such that the x-coordinates of points in the assembled sequence will not decrease. Help him with that. Note that each element of the initial sequences should be used exactly once in the assembled sequence.Dima considers two assembled sequences (p1, q1), (p2, q2), ..., (p2·n, q2·n) and (x1, y1), (x2, y2), ..., (x2·n, y2·n) distinct, if there is such i (1 ≤ i ≤ 2·n), that (pi, qi) ≠ (xi, yi).As the answer can be rather large, print the remainder from dividing the answer by number m.",[]238"Our old friend Alexey has finally entered the University of City N — the Berland capital. Alexey expected his father to get him a place to live in but his father said it was high time for Alexey to practice some financial independence. So, Alexey is living in a dorm. The dorm has exactly one straight dryer — a 100 centimeter long rope to hang clothes on. The dryer has got a coordinate system installed: the leftmost end of the dryer has coordinate 0, and the opposite end has coordinate 100. Overall, the university has n students. Dean's office allows i-th student to use the segment (li, ri) of the dryer. However, the dean's office actions are contradictory and now one part of the dryer can belong to multiple students!Alexey don't like when someone touch his clothes. That's why he want make it impossible to someone clothes touch his ones. So Alexey wonders: what is the total length of the parts of the dryer that he may use in a such way that clothes of the others (n - 1) students aren't drying there. Help him! Note that Alexey, as the most respected student, has number 1.",[]239"You are given an integer $$$x$$$ and an array of integers $$$a_1, a_2, \ldots, a_n$$$. You have to determine if the number $$$a_1! + a_2! + \ldots + a_n!$$$ is divisible by $$$x!$$$.Here $$$k!$$$ is a factorial of $$$k$$$ — the product of all positive integers less than or equal to $$$k$$$. For example, $$$3! = 1 \cdot 2 \cdot 3 = 6$$$, and $$$5! = 1 \cdot 2 \cdot 3 \cdot 4 \cdot 5 = 120$$$.","['math', 'number theory']"240"Given an array of integer $$$a_1, a_2, \ldots, a_n$$$. In one operation you can make $$$a_i := a_i + 1$$$ if $$$i < n$$$ and $$$a_i \leq a_{i + 1}$$$, or $$$i = n$$$ and $$$a_i \leq a_1$$$.You need to check whether the array $$$a_1, a_2, \ldots, a_n$$$ can become equal to the array $$$b_1, b_2, \ldots, b_n$$$ in some number of operations (possibly, zero). Two arrays $$$a$$$ and $$$b$$$ of length $$$n$$$ are called equal if $$$a_i = b_i$$$ for all integers $$$i$$$ from $$$1$$$ to $$$n$$$.",[]241"Now Dmitry has a session, and he has to pass $$$n$$$ exams. The session starts on day $$$1$$$ and lasts $$$d$$$ days. The $$$i$$$th exam will take place on the day of $$$a_i$$$ ($$$1 \le a_i \le d$$$), all $$$a_i$$$ — are different.    Sample, where $$$n=3$$$, $$$d=12$$$, $$$a=[3,5,9]$$$. Orange — exam days. Before the first exam Dmitry will rest $$$2$$$ days, before the second he will rest $$$1$$$ day and before the third he will rest $$$3$$$ days. For the session schedule, Dmitry considers a special value $$$\mu$$$ — the smallest of the rest times before the exam for all exams. For example, for the image above, $$$\mu=1$$$. In other words, for the schedule, he counts exactly $$$n$$$ numbers  — how many days he rests between the exam $$$i-1$$$ and $$$i$$$ (for $$$i=0$$$ between the start of the session and the exam $$$i$$$). Then it finds $$$\mu$$$ — the minimum among these $$$n$$$ numbers.Dmitry believes that he can improve the schedule of the session. He may ask to change the date of one exam (change one arbitrary value of $$$a_i$$$). Help him change the date so that all $$$a_i$$$ remain different, and the value of $$$\mu$$$ is as large as possible.For example, for the schedule above, it is most advantageous for Dmitry to move the second exam to the very end of the session. The new schedule will take the form:    Now the rest periods before exams are equal to $$$[2,2,5]$$$. So, $$$\mu=2$$$. Dmitry can leave the proposed schedule unchanged (if there is no way to move one exam so that it will lead to an improvement in the situation).",['math']242"Student Valera is an undergraduate student at the University. His end of term exams are approaching and he is to pass exactly n exams. Valera is a smart guy, so he will be able to pass any exam he takes on his first try. Besides, he can take several exams on one day, and in any order.According to the schedule, a student can take the exam for the i-th subject on the day number ai. However, Valera has made an arrangement with each teacher and the teacher of the i-th subject allowed him to take an exam before the schedule time on day bi (bi < ai). Thus, Valera can take an exam for the i-th subject either on day ai, or on day bi. All the teachers put the record of the exam in the student's record book on the day of the actual exam and write down the date of the mark as number ai.Valera believes that it would be rather strange if the entries in the record book did not go in the order of non-decreasing date. Therefore Valera asks you to help him. Find the minimum possible value of the day when Valera can take the final exam if he takes exams so that all the records in his record book go in the order of non-decreasing date.",[]243"You play a computer game. In this game, you lead a party of $$$m$$$ heroes, and you have to clear a dungeon with $$$n$$$ monsters. Each monster is characterized by its power $$$a_i$$$. Each hero is characterized by his power $$$p_i$$$ and endurance $$$s_i$$$.The heroes clear the dungeon day by day. In the beginning of each day, you choose a hero (exactly one) who is going to enter the dungeon this day.When the hero enters the dungeon, he is challenged by the first monster which was not defeated during the previous days (so, if the heroes have already defeated $$$k$$$ monsters, the hero fights with the monster $$$k + 1$$$). When the hero fights the monster, there are two possible outcomes:  if the monster's power is strictly greater than the hero's power, the hero retreats from the dungeon. The current day ends;  otherwise, the monster is defeated. After defeating a monster, the hero either continues fighting with the next monster or leaves the dungeon. He leaves the dungeon either if he has already defeated the number of monsters equal to his endurance during this day (so, the $$$i$$$-th hero cannot defeat more than $$$s_i$$$ monsters during each day), or if all monsters are defeated — otherwise, he fights with the next monster. When the hero leaves the dungeon, the current day ends.Your goal is to defeat the last monster. What is the minimum number of days that you need to achieve your goal? Each day you have to use exactly one hero; it is possible that some heroes don't fight the monsters at all. Each hero can be used arbitrary number of times.",[]244"Little Tanya decided to present her dad a postcard on his Birthday. She has already created a message — string s of length n, consisting of uppercase and lowercase English letters. Tanya can't write yet, so she found a newspaper and decided to cut out the letters and glue them into the postcard to achieve string s. The newspaper contains string t, consisting of uppercase and lowercase English letters. We know that the length of string t greater or equal to the length of the string s.The newspaper may possibly have too few of some letters needed to make the text and too many of some other letters. That's why Tanya wants to cut some n letters out of the newspaper and make a message of length exactly n, so that it looked as much as possible like s. If the letter in some position has correct value and correct letter case (in the string s and in the string that Tanya will make), then she shouts joyfully ""YAY!"", and if the letter in the given position has only the correct value but it is in the wrong case, then the girl says ""WHOOPS"".Tanya wants to make such message that lets her shout ""YAY!"" as much as possible. If there are multiple ways to do this, then her second priority is to maximize the number of times she says ""WHOOPS"". Your task is to help Tanya make the message.",['strings']245"Jzzhu is the president of country A. There are n cities numbered from 1 to n in his country. City 1 is the capital of A. Also there are m roads connecting the cities. One can go from city ui to vi (and vise versa) using the i-th road, the length of this road is xi. Finally, there are k train routes in the country. One can use the i-th train route to go from capital of the country to city si (and vise versa), the length of this route is yi.Jzzhu doesn't want to waste the money of the country, so he is going to close some of the train routes. Please tell Jzzhu the maximum number of the train routes which can be closed under the following condition: the length of the shortest path from every city to the capital mustn't change.",['graphs']246"You got a job as a marketer in a pet shop, and your current task is to boost sales of cat food. One of the strategies is to sell cans of food in packs with discounts. Suppose you decided to sell packs with $$$a$$$ cans in a pack with a discount and some customer wants to buy $$$x$$$ cans of cat food. Then he follows a greedy strategy:   he buys $$$\left\lfloor \frac{x}{a} \right\rfloor$$$ packs with a discount;  then he wants to buy the remaining $$$(x \bmod a)$$$ cans one by one. $$$\left\lfloor \frac{x}{a} \right\rfloor$$$ is $$$x$$$ divided by $$$a$$$ rounded down, $$$x \bmod a$$$ is the remainer of $$$x$$$ divided by $$$a$$$.But customers are greedy in general, so if the customer wants to buy $$$(x \bmod a)$$$ cans one by one and it happens that $$$(x \bmod a) \ge \frac{a}{2}$$$ he decides to buy the whole pack of $$$a$$$ cans (instead of buying $$$(x \bmod a)$$$ cans). It makes you, as a marketer, happy since the customer bought more than he wanted initially.You know that each of the customers that come to your shop can buy any number of cans from $$$l$$$ to $$$r$$$ inclusive. Can you choose such size of pack $$$a$$$ that each customer buys more cans than they wanted initially?",['math']247"Team Red and Team Blue competed in a competitive FPS. Their match was streamed around the world. They played a series of $$$n$$$ matches.In the end, it turned out Team Red won $$$r$$$ times and Team Blue won $$$b$$$ times. Team Blue was less skilled than Team Red, so $$$b$$$ was strictly less than $$$r$$$.You missed the stream since you overslept, but you think that the match must have been neck and neck since so many people watched it. So you imagine a string of length $$$n$$$ where the $$$i$$$-th character denotes who won the $$$i$$$-th match  — it is R if Team Red won or B if Team Blue won. You imagine the string was such that the maximum number of times a team won in a row was as small as possible. For example, in the series of matches RBBRRRB, Team Red won $$$3$$$ times in a row, which is the maximum.You must find a string satisfying the above conditions. If there are multiple answers, print any.",['math']248"You are given two arrays $$$a$$$ and $$$b$$$ of length $$$n$$$. Array $$$a$$$ contains each odd integer from $$$1$$$ to $$$2n$$$ in an arbitrary order, and array $$$b$$$ contains each even integer from $$$1$$$ to $$$2n$$$ in an arbitrary order.You can perform the following operation on those arrays:   choose one of the two arrays  pick an index $$$i$$$ from $$$1$$$ to $$$n-1$$$  swap the $$$i$$$-th and the $$$(i+1)$$$-th elements of the chosen array  Compute the minimum number of operations needed to make array $$$a$$$ lexicographically smaller than array $$$b$$$.For two different arrays $$$x$$$ and $$$y$$$ of the same length $$$n$$$, we say that $$$x$$$ is lexicographically smaller than $$$y$$$ if in the first position where $$$x$$$ and $$$y$$$ differ, the array $$$x$$$ has a smaller element than the corresponding element in $$$y$$$.",['math']249"Shuseki Kingdom is the world's leading nation for innovation and technology. There are n cities in the kingdom, numbered from 1 to n.Thanks to Mr. Kitayuta's research, it has finally become possible to construct teleportation pipes between two cities. A teleportation pipe will connect two cities unidirectionally, that is, a teleportation pipe from city x to city y cannot be used to travel from city y to city x. The transportation within each city is extremely developed, therefore if a pipe from city x to city y and a pipe from city y to city z are both constructed, people will be able to travel from city x to city z instantly.Mr. Kitayuta is also involved in national politics. He considers that the transportation between the m pairs of city (ai, bi) (1 ≤ i ≤ m) is important. He is planning to construct teleportation pipes so that for each important pair (ai, bi), it will be possible to travel from city ai to city bi by using one or more teleportation pipes (but not necessarily from city bi to city ai). Find the minimum number of teleportation pipes that need to be constructed. So far, no teleportation pipe has been constructed, and there is no other effective transportation between cities.",[]250"Due to the coronavirus pandemic, city authorities obligated citizens to keep a social distance. The mayor of the city Semyon wants to light up Gluharniki park so that people could see each other even at night to keep the social distance.The park is a rectangular table with $$$n$$$ rows and $$$m$$$ columns, where the cells of the table are squares, and the boundaries between the cells are streets. External borders are also streets. Every street has length $$$1$$$. For example, park with $$$n=m=2$$$ has $$$12$$$ streets.You were assigned to develop a plan for lighting the park. You can put lanterns in the middle of the streets. The lamp lights two squares near it (or only one square if it stands on the border of the park).    The park sizes are: $$$n=4$$$, $$$m=5$$$. The lighted squares are marked yellow. Please note that all streets have length $$$1$$$. Lanterns are placed in the middle of the streets. In the picture not all the squares are lit. Semyon wants to spend the least possible amount of money on lighting but also wants people throughout the park to keep a social distance. So he asks you to find the minimum number of lanterns that are required to light all the squares.",['math']251"Andryusha is an orderly boy and likes to keep things in their place.Today he faced a problem to put his socks in the wardrobe. He has n distinct pairs of socks which are initially in a bag. The pairs are numbered from 1 to n. Andryusha wants to put paired socks together and put them in the wardrobe. He takes the socks one by one from the bag, and for each sock he looks whether the pair of this sock has been already took out of the bag, or not. If not (that means the pair of this sock is still in the bag), he puts the current socks on the table in front of him. Otherwise, he puts both socks from the pair to the wardrobe.Andryusha remembers the order in which he took the socks from the bag. Can you tell him what is the maximum number of socks that were on the table at the same time? ",[]252In the country there are n cities and m bidirectional roads between them. Each city has an army. Army of the i-th city consists of ai soldiers. Now soldiers roam. After roaming each soldier has to either stay in his city or to go to the one of neighboring cities by at moving along at most one road.Check if is it possible that after roaming there will be exactly bi soldiers in the i-th city.,"['math', 'graphs']"253"ZS the Coder and Chris the Baboon has explored Udayland for quite some time. They realize that it consists of n towns numbered from 1 to n. There are n directed roads in the Udayland. i-th of them goes from town i to some other town ai (ai ≠ i). ZS the Coder can flip the direction of any road in Udayland, i.e. if it goes from town A to town B before the flip, it will go from town B to town A after.ZS the Coder considers the roads in the Udayland confusing, if there is a sequence of distinct towns A1, A2, ..., Ak (k > 1) such that for every 1 ≤ i < k there is a road from town Ai to town Ai + 1 and another road from town Ak to town A1. In other words, the roads are confusing if some of them form a directed cycle of some towns.Now ZS the Coder wonders how many sets of roads (there are 2n variants) in initial configuration can he choose to flip such that after flipping each road in the set exactly once, the resulting network will not be confusing.Note that it is allowed that after the flipping there are more than one directed road from some town and possibly some towns with no roads leading out of it, or multiple roads between any pair of cities.","['math', 'graphs']"254"You are given a rooted tree consisting of $$$n$$$ vertices. Vertices are numbered from $$$1$$$ to $$$n$$$. Any vertex can be the root of a tree.A tree is a connected undirected graph without cycles. A rooted tree is a tree with a selected vertex, which is called the root.The tree is specified by an array of parents $$$p$$$ containing $$$n$$$ numbers: $$$p_i$$$ is a parent of the vertex with the index $$$i$$$. The parent of a vertex $$$u$$$ is a vertex that is the next vertex on the shortest path from $$$u$$$ to the root. For example, on the simple path from $$$5$$$ to $$$3$$$ (the root), the next vertex would be $$$1$$$, so the parent of $$$5$$$ is $$$1$$$.The root has no parent, so for it, the value of $$$p_i$$$ is $$$i$$$ (the root is the only vertex for which $$$p_i=i$$$).Find such a set of paths that:  each vertex belongs to exactly one path, each path can contain one or more vertices;  in each path each next vertex — is a son of the current vertex (that is, paths always lead down — from parent to son);  number of paths is minimal. For example, if $$$n=5$$$ and $$$p=[3, 1, 3, 3, 1]$$$, then the tree can be divided into three paths:   $$$3 \rightarrow 1 \rightarrow 5$$$ (path of $$$3$$$ vertices),  $$$4$$$ (path of $$$1$$$ vertices).  $$$2$$$ (path of $$$1$$$ vertices).     Example of splitting a root tree into three paths for $$$n=5$$$, the root of the tree — node $$$3$$$. ","['graphs', 'trees']"255"You are given a positive integer $$$m$$$ and two integer sequence: $$$a=[a_1, a_2, \ldots, a_n]$$$ and $$$b=[b_1, b_2, \ldots, b_n]$$$. Both of these sequence have a length $$$n$$$.Permutation is a sequence of $$$n$$$ different positive integers from $$$1$$$ to $$$n$$$. For example, these sequences are permutations: $$$[1]$$$, $$$[1,2]$$$, $$$[2,1]$$$, $$$[6,7,3,4,1,2,5]$$$. These are not: $$$[0]$$$, $$$[1,1]$$$, $$$[2,3]$$$.You need to find the non-negative integer $$$x$$$, and increase all elements of $$$a_i$$$ by $$$x$$$, modulo $$$m$$$ (i.e. you want to change $$$a_i$$$ to $$$(a_i + x) \bmod m$$$), so it would be possible to rearrange elements of $$$a$$$ to make it equal $$$b$$$, among them you need to find the smallest possible $$$x$$$.In other words, you need to find the smallest non-negative integer $$$x$$$, for which it is possible to find some permutation $$$p=[p_1, p_2, \ldots, p_n]$$$, such that for all $$$1 \leq i \leq n$$$, $$$(a_i + x) \bmod m = b_{p_i}$$$, where $$$y \bmod m$$$ — remainder of division of $$$y$$$ by $$$m$$$.For example, if $$$m=3$$$, $$$a = [0, 0, 2, 1], b = [2, 0, 1, 1]$$$, you can choose $$$x=1$$$, and $$$a$$$ will be equal to $$$[1, 1, 0, 2]$$$ and you can rearrange it to make it equal $$$[2, 0, 1, 1]$$$, which is equal to $$$b$$$.",[]256"Wu got hungry after an intense training session, and came to a nearby store to buy his favourite instant noodles. After Wu paid for his purchase, the cashier gave him an interesting task.You are given a bipartite graph with positive integers in all vertices of the right half. For a subset $$$S$$$ of vertices of the left half we define $$$N(S)$$$ as the set of all vertices of the right half adjacent to at least one vertex in $$$S$$$, and $$$f(S)$$$ as the sum of all numbers in vertices of $$$N(S)$$$. Find the greatest common divisor of $$$f(S)$$$ for all possible non-empty subsets $$$S$$$ (assume that GCD of empty set is $$$0$$$).Wu is too tired after his training to solve this problem. Help him!","['math', 'graphs', 'number theory']"257"  William has two numbers $$$a$$$ and $$$b$$$ initially both equal to zero. William mastered performing three different operations with them quickly. Before performing each operation some positive integer $$$k$$$ is picked, which is then used to perform one of the following operations: (note, that for each operation you can choose a new positive integer $$$k$$$)  add number $$$k$$$ to both $$$a$$$ and $$$b$$$, or  add number $$$k$$$ to $$$a$$$ and subtract $$$k$$$ from $$$b$$$, or  add number $$$k$$$ to $$$b$$$ and subtract $$$k$$$ from $$$a$$$. Note that after performing operations, numbers $$$a$$$ and $$$b$$$ may become negative as well.William wants to find out the minimal number of operations he would have to perform to make $$$a$$$ equal to his favorite number $$$c$$$ and $$$b$$$ equal to his second favorite number $$$d$$$.",['math']258"You are given a boolean function of three variables which is defined by its truth table. You need to find an expression of minimum length that equals to this function. The expression may consist of:   Operation AND ('&', ASCII code 38)  Operation OR ('|', ASCII code 124)  Operation NOT ('!', ASCII code 33)  Variables x, y and z (ASCII codes 120-122)  Parentheses ('(', ASCII code 40, and ')', ASCII code 41) If more than one expression of minimum length exists, you should find the lexicographically smallest one.Operations have standard priority. NOT has the highest priority, then AND goes, and OR has the lowest priority. The expression should satisfy the following grammar:E ::= E '|' T | TT ::= T '&' F | FF ::= '!' F | '(' E ')' | 'x' | 'y' | 'z'",[]259"Polycarp is playing a new computer game. This game has $$$n$$$ stones in a row. The stone on the position $$$i$$$ has integer power $$$a_i$$$. The powers of all stones are distinct.Each turn Polycarp can destroy either stone on the first position or stone on the last position (in other words, either the leftmost or the rightmost stone). When Polycarp destroys the stone it does not exist any more.Now, Polycarp wants two achievements. He gets them if he destroys the stone with the least power and the stone with the greatest power. Help Polycarp find out what is the minimum number of moves he should make in order to achieve his goal.For example, if $$$n = 5$$$ and $$$a = [1, 5, 4, 3, 2]$$$, then Polycarp could make the following moves:   Destroy the leftmost stone. After this move $$$a = [5, 4, 3, 2]$$$;  Destroy the rightmost stone. After this move $$$a = [5, 4, 3]$$$;  Destroy the leftmost stone. After this move $$$a = [4, 3]$$$. Polycarp destroyed the stones with the greatest and least power, so he can end the game. Please note that in the example above, you can complete the game in two steps. For example:   Destroy the leftmost stone. After this move $$$a = [5, 4, 3, 2]$$$;  Destroy the leftmost stone. After this move $$$a = [4, 3, 2]$$$. Polycarp destroyed the stones with the greatest and least power, so he can end the game. ",[]260"You are given two integers $$$a$$$ and $$$b$$$.In one move, you can choose some integer $$$k$$$ from $$$1$$$ to $$$10$$$ and add it to $$$a$$$ or subtract it from $$$a$$$. In other words, you choose an integer $$$k \in [1; 10]$$$ and perform $$$a := a + k$$$ or $$$a := a - k$$$. You may use different values of $$$k$$$ in different moves.Your task is to find the minimum number of moves required to obtain $$$b$$$ from $$$a$$$.You have to answer $$$t$$$ independent test cases.",['math']261"You are given two strings $$$A$$$ and $$$B$$$ representing essays of two students who are suspected cheaters. For any two strings $$$C$$$, $$$D$$$ we define their similarity score $$$S(C,D)$$$ as $$$4\cdot LCS(C,D) - |C| - |D|$$$, where $$$LCS(C,D)$$$ denotes the length of the Longest Common Subsequence of strings $$$C$$$ and $$$D$$$. You believe that only some part of the essays could have been copied, therefore you're interested in their substrings.Calculate the maximal similarity score over all pairs of substrings. More formally, output maximal $$$S(C, D)$$$ over all pairs $$$(C, D)$$$, where $$$C$$$ is some substring of $$$A$$$, and $$$D$$$ is some substring of $$$B$$$. If $$$X$$$ is a string, $$$|X|$$$ denotes its length.A string $$$a$$$ is a substring of a string $$$b$$$ if $$$a$$$ can be obtained from $$$b$$$ by deletion of several (possibly, zero or all) characters from the beginning and several (possibly, zero or all) characters from the end.A string $$$a$$$ is a subsequence of a string $$$b$$$ if $$$a$$$ can be obtained from $$$b$$$ by deletion of several (possibly, zero or all) characters. Pay attention to the difference between the substring and subsequence, as they both appear in the problem statement. You may wish to read the Wikipedia page about the Longest Common Subsequence problem.",['strings']262"You are given an array $$$a$$$, consisting of $$$n$$$ positive integers.Let's call a concatenation of numbers $$$x$$$ and $$$y$$$ the number that is obtained by writing down numbers $$$x$$$ and $$$y$$$ one right after another without changing the order. For example, a concatenation of numbers $$$12$$$ and $$$3456$$$ is a number $$$123456$$$.Count the number of ordered pairs of positions $$$(i, j)$$$ ($$$i \neq j$$$) in array $$$a$$$ such that the concatenation of $$$a_i$$$ and $$$a_j$$$ is divisible by $$$k$$$.",['math']263"Not so long ago, Vlad had a birthday, for which he was presented with a package of candies. There were $$$n$$$ types of candies, there are $$$a_i$$$ candies of the type $$$i$$$ ($$$1 \le i \le n$$$).Vlad decided to eat exactly one candy every time, choosing any of the candies of a type that is currently the most frequent (if there are several such types, he can choose any of them). To get the maximum pleasure from eating, Vlad does not want to eat two candies of the same type in a row.Help him figure out if he can eat all the candies without eating two identical candies in a row.",['math']264"While doing some spring cleaning, Daniel found an old calculator that he loves so much. However, it seems like it is broken. When he tries to compute $$$1 + 3$$$ using the calculator, he gets $$$2$$$ instead of $$$4$$$. But when he tries computing $$$1 + 4$$$, he gets the correct answer, $$$5$$$. Puzzled by this mystery, he opened up his calculator and found the answer to the riddle: the full adders became half adders! So, when he tries to compute the sum $$$a + b$$$ using the calculator, he instead gets the xorsum $$$a \oplus b$$$ (read the definition by the link: https://en.wikipedia.org/wiki/Exclusive_or).As he saw earlier, the calculator sometimes gives the correct answer. And so, he wonders, given integers $$$l$$$ and $$$r$$$, how many pairs of integers $$$(a, b)$$$ satisfy the following conditions: $$$$$$a + b = a \oplus b$$$$$$ $$$$$$l \leq a \leq r$$$$$$ $$$$$$l \leq b \leq r$$$$$$However, Daniel the Barman is going to the bar and will return in two hours. He tells you to solve the problem before he returns, or else you will have to enjoy being blocked.",[]265"Polycarp has a string $$$s$$$ consisting of lowercase Latin letters.He encodes it using the following algorithm.He goes through the letters of the string $$$s$$$ from left to right and for each letter Polycarp considers its number in the alphabet:  if the letter number is single-digit number (less than $$$10$$$), then just writes it out;  if the letter number is a two-digit number (greater than or equal to $$$10$$$), then it writes it out and adds the number 0 after. For example, if the string $$$s$$$ is code, then Polycarp will encode this string as follows:  'c' — is the $$$3$$$-rd letter of the alphabet. Consequently, Polycarp adds 3 to the code (the code becomes equal to 3);  'o' — is the $$$15$$$-th letter of the alphabet. Consequently, Polycarp adds 15 to the code and also 0 (the code becomes 3150);  'd' — is the $$$4$$$-th letter of the alphabet. Consequently, Polycarp adds 4 to the code (the code becomes 31504);  'e' — is the $$$5$$$-th letter of the alphabet. Therefore, Polycarp adds 5 to the code (the code becomes 315045). Thus, code of string code is 315045.You are given a string $$$t$$$ resulting from encoding the string $$$s$$$. Your task is to decode it (get the original string $$$s$$$ by $$$t$$$).",['strings']266"A telephone number is a sequence of exactly $$$11$$$ digits such that its first digit is 8.Vasya and Petya are playing a game. Initially they have a string $$$s$$$ of length $$$n$$$ ($$$n$$$ is odd) consisting of digits. Vasya makes the first move, then players alternate turns. In one move the player must choose a character and erase it from the current string. For example, if the current string 1121, after the player's move it may be 112, 111 or 121. The game ends when the length of string $$$s$$$ becomes 11. If the resulting string is a telephone number, Vasya wins, otherwise Petya wins.You have to determine if Vasya has a winning strategy (that is, if Vasya can win the game no matter which characters Petya chooses during his moves).",['games']267"Sam has been teaching Jon the Game of Stones to sharpen his mind and help him devise a strategy to fight the white walkers. The rules of this game are quite simple:  The game starts with n piles of stones indexed from 1 to n. The i-th pile contains si stones. The players make their moves alternatively. A move is considered as removal of some number of stones from a pile. Removal of 0 stones does not count as a move. The player who is unable to make a move loses.Now Jon believes that he is ready for battle, but Sam does not think so. To prove his argument, Sam suggested that they play a modified version of the game.In this modified version, no move can be made more than once on a pile. For example, if 4 stones are removed from a pile, 4 stones cannot be removed from that pile again.Sam sets up the game and makes the first move. Jon believes that Sam is just trying to prevent him from going to battle. Jon wants to know if he can win if both play optimally.",['games']268"Anatoly lives in the university dorm as many other students do. As you know, cockroaches are also living there together with students. Cockroaches might be of two colors: black and red. There are n cockroaches living in Anatoly's room.Anatoly just made all his cockroaches to form a single line. As he is a perfectionist, he would like the colors of cockroaches in the line to alternate. He has a can of black paint and a can of red paint. In one turn he can either swap any two cockroaches, or take any single cockroach and change it's color.Help Anatoly find out the minimum number of turns he needs to make the colors of cockroaches in the line alternate.",[]269"Little penguin Polo likes permutations. But most of all he likes permutations of integers from 0 to n, inclusive.For permutation p = p0, p1, ..., pn, Polo has defined its beauty — number .Expression  means applying the operation of bitwise excluding ""OR"" to numbers x and y. This operation exists in all modern programming languages, for example, in language C++ and Java it is represented as ""^"" and in Pascal — as ""xor"".Help him find among all permutations of integers from 0 to n the permutation with the maximum beauty.",['math']270"Let $$$a$$$ be a matrix of size $$$r \times c$$$ containing positive integers, not necessarily distinct. Rows of the matrix are numbered from $$$1$$$ to $$$r$$$, columns are numbered from $$$1$$$ to $$$c$$$. We can construct an array $$$b$$$ consisting of $$$r + c$$$ integers as follows: for each $$$i \in [1, r]$$$, let $$$b_i$$$ be the greatest common divisor of integers in the $$$i$$$-th row, and for each $$$j \in [1, c]$$$ let $$$b_{r+j}$$$ be the greatest common divisor of integers in the $$$j$$$-th column. We call the matrix diverse if all $$$r + c$$$ numbers $$$b_k$$$ ($$$k \in [1, r + c]$$$) are pairwise distinct. The magnitude of a matrix equals to the maximum of $$$b_k$$$.For example, suppose we have the following matrix: $$$\begin{pmatrix} 2 & 9 & 7\\ 4 & 144 & 84 \end{pmatrix}$$$ We construct the array $$$b$$$:  $$$b_1$$$ is the greatest common divisor of $$$2$$$, $$$9$$$, and $$$7$$$, that is $$$1$$$;  $$$b_2$$$ is the greatest common divisor of $$$4$$$, $$$144$$$, and $$$84$$$, that is $$$4$$$;  $$$b_3$$$ is the greatest common divisor of $$$2$$$ and $$$4$$$, that is $$$2$$$;  $$$b_4$$$ is the greatest common divisor of $$$9$$$ and $$$144$$$, that is $$$9$$$;  $$$b_5$$$ is the greatest common divisor of $$$7$$$ and $$$84$$$, that is $$$7$$$. So $$$b = [1, 4, 2, 9, 7]$$$. All values in this array are distinct, so the matrix is diverse. The magnitude is equal to $$$9$$$.For a given $$$r$$$ and $$$c$$$, find a diverse matrix that minimises the magnitude. If there are multiple solutions, you may output any of them. If there are no solutions, output a single integer $$$0$$$. ","['math', 'number theory']"271"Arkady decides to observe a river for n consecutive days. The river's water level on each day is equal to some real value.Arkady goes to the riverside each day and makes a mark on the side of the channel at the height of the water level, but if it coincides with a mark made before, no new mark is created. The water does not wash the marks away. Arkady writes down the number of marks strictly above the water level each day, on the i-th day this value is equal to mi.Define di as the number of marks strictly under the water level on the i-th day. You are to find out the minimum possible sum of di over all days. There are no marks on the channel before the first day.",[]272"Alice guesses the strings that Bob made for her.At first, Bob came up with the secret string $$$a$$$ consisting of lowercase English letters. The string $$$a$$$ has a length of $$$2$$$ or more characters. Then, from string $$$a$$$ he builds a new string $$$b$$$ and offers Alice the string $$$b$$$ so that she can guess the string $$$a$$$.Bob builds $$$b$$$ from $$$a$$$ as follows: he writes all the substrings of length $$$2$$$ of the string $$$a$$$ in the order from left to right, and then joins them in the same order into the string $$$b$$$.For example, if Bob came up with the string $$$a$$$=""abac"", then all the substrings of length $$$2$$$ of the string $$$a$$$ are: ""ab"", ""ba"", ""ac"". Therefore, the string $$$b$$$=""abbaac"".You are given the string $$$b$$$. Help Alice to guess the string $$$a$$$ that Bob came up with. It is guaranteed that $$$b$$$ was built according to the algorithm given above. It can be proved that the answer to the problem is unique.",['strings']273"Momiji has got a rooted tree, consisting of n nodes. The tree nodes are numbered by integers from 1 to n. The root has number 1. Momiji decided to play a game on this tree.The game consists of several steps. On each step, Momiji chooses one of the remaining tree nodes (let's denote it by v) and removes all the subtree nodes with the root in node v from the tree. Node v gets deleted as well. The game finishes when the tree has no nodes left. In other words, the game finishes after the step that chooses the node number 1.Each time Momiji chooses a new node uniformly among all the remaining nodes. Your task is to find the expectation of the number of steps in the described game.","['math', 'trees', 'probabilities']"274"It is the hard version of the problem. The only difference is that in this version $$$a_i \le 10^9$$$.You are given an array of $$$n$$$ integers $$$a_0, a_1, a_2, \ldots a_{n - 1}$$$. Bryap wants to find the longest beautiful subsequence in the array.An array $$$b = [b_0, b_1, \ldots, b_{m-1}]$$$, where $$$0 \le b_0 < b_1 < \ldots < b_{m - 1} < n$$$, is a subsequence of length $$$m$$$ of the array $$$a$$$.Subsequence $$$b = [b_0, b_1, \ldots, b_{m-1}]$$$ of length $$$m$$$ is called beautiful, if the following condition holds:   For any $$$p$$$ ($$$0 \le p < m - 1$$$) holds: $$$a_{b_p} \oplus b_{p+1} < a_{b_{p+1}} \oplus b_p$$$. Here $$$a \oplus b$$$ denotes the bitwise XOR of $$$a$$$ and $$$b$$$. For example, $$$2 \oplus 4 = 6$$$ and $$$3 \oplus 1=2$$$.Bryap is a simple person so he only wants to know the length of the longest such subsequence. Help Bryap and find the answer to his question.","['strings', 'trees']"275"Sereja has a sequence that consists of n positive integers, a1, a2, ..., an. First Sereja took a piece of squared paper and wrote all distinct non-empty non-decreasing subsequences of sequence a. Then for each sequence written on the squared paper, Sereja wrote on a piece of lines paper all sequences that do not exceed it.A sequence of positive integers x = x1, x2, ..., xr doesn't exceed a sequence of positive integers y = y1, y2, ..., yr, if the following inequation holds: x1 ≤ y1, x2 ≤ y2, ..., xr ≤ yr.Now Sereja wonders, how many sequences are written on the lines piece of paper. Help Sereja, find the required quantity modulo 1000000007 (109 + 7). ",[]276"Polycarp is practicing his problem solving skill. He has a list of $$$n$$$ problems with difficulties $$$a_1, a_2, \dots, a_n$$$, respectively. His plan is to practice for exactly $$$k$$$ days. Each day he has to solve at least one problem from his list. Polycarp solves the problems in the order they are given in his list, he cannot skip any problem from his list. He has to solve all $$$n$$$ problems in exactly $$$k$$$ days.Thus, each day Polycarp solves a contiguous sequence of (consecutive) problems from the start of the list. He can't skip problems or solve them multiple times. As a result, in $$$k$$$ days he will solve all the $$$n$$$ problems.The profit of the $$$j$$$-th day of Polycarp's practice is the maximum among all the difficulties of problems Polycarp solves during the $$$j$$$-th day (i.e. if he solves problems with indices from $$$l$$$ to $$$r$$$ during a day, then the profit of the day is $$$\max\limits_{l \le i \le r}a_i$$$). The total profit of his practice is the sum of the profits over all $$$k$$$ days of his practice.You want to help Polycarp to get the maximum possible total profit over all valid ways to solve problems. Your task is to distribute all $$$n$$$ problems between $$$k$$$ days satisfying the conditions above in such a way, that the total profit is maximum.For example, if $$$n = 8, k = 3$$$ and $$$a = [5, 4, 2, 6, 5, 1, 9, 2]$$$, one of the possible distributions with maximum total profit is: $$$[5, 4, 2], [6, 5], [1, 9, 2]$$$. Here the total profit equals $$$5 + 6 + 9 = 20$$$.",[]277"Vasya lives in a strange world. The year has n months and the i-th month has ai days. Vasya got a New Year present — the clock that shows not only the time, but also the date.The clock's face can display any number from 1 to d. It is guaranteed that ai ≤ d for all i from 1 to n. The clock does not keep information about the current month, so when a new day comes, it simply increases the current day number by one. The clock cannot display number d + 1, so after day number d it shows day 1 (the current day counter resets). The mechanism of the clock allows you to increase the day number by one manually. When you execute this operation, day d is also followed by day 1.Vasya begins each day checking the day number on the clock. If the day number on the clock does not match the actual day number in the current month, then Vasya manually increases it by one. Vasya is persistent and repeats this operation until the day number on the clock matches the actual number of the current day in the current month.A year passed and Vasya wonders how many times he manually increased the day number by one, from the first day of the first month to the last day of the n-th month inclusive, considering that on the first day of the first month the clock display showed day 1.",[]278"  While performing complex market analysis William encountered the following problem:For a given array $$$a$$$ of size $$$n$$$ and a natural number $$$e$$$, calculate the number of pairs of natural numbers $$$(i, k)$$$ which satisfy the following conditions:   $$$1 \le i, k$$$  $$$i + e \cdot k \le n$$$.  Product $$$a_i \cdot a_{i + e} \cdot a_{i + 2 \cdot e} \cdot \ldots \cdot a_{i + k \cdot e} $$$ is a prime number. A prime number (or a prime) is a natural number greater than 1 that is not a product of two smaller natural numbers.",['number theory']279"As it has been found out recently, all the Berland's current economical state can be described using a simple table n × m in size. n — the number of days in each Berland month, m — the number of months. Thus, a table cell corresponds to a day and a month of the Berland's year. Each cell will contain either 1, or -1, which means the state's gains in a particular month, on a particular day. 1 corresponds to profits, -1 corresponds to losses. It turned out important for successful development to analyze the data on the state of the economy of the previous year, however when the treasurers referred to the archives to retrieve the data, it turned out that the table had been substantially damaged. In some table cells the number values had faded and were impossible to be deciphered. It is known that the number of cells in which the data had been preserved is strictly less than max(n, m). However, there is additional information — the product of the numbers in each line and column equaled -1. Your task is to find out how many different tables may conform to the preserved data. As the answer to the task can be quite large, you have to find it modulo p.",[]280"Please notice the unusual memory limit of this problem.Orac likes games. Recently he came up with the new game, ""Game of Life"".You should play this game on a black and white grid with $$$n$$$ rows and $$$m$$$ columns. Each cell is either black or white.For each iteration of the game (the initial iteration is $$$0$$$), the color of each cell will change under the following rules: If there are no adjacent cells with the same color as this cell on the current iteration, the color of it on the next iteration will be the same. Otherwise, the color of the cell on the next iteration will be different.Two cells are adjacent if they have a mutual edge.Now Orac has set an initial situation, and he wants to know for the cell $$$(i,j)$$$ (in $$$i$$$-th row and $$$j$$$-th column), what will be its color at the iteration $$$p$$$. He may ask you these questions several times. ",['graphs']281"Recently in school Alina has learned what are the persistent data structures: they are data structures that always preserves the previous version of itself and access to it when it is modified.After reaching home Alina decided to invent her own persistent data structure. Inventing didn't take long: there is a bookcase right behind her bed. Alina thinks that the bookcase is a good choice for a persistent data structure. Initially the bookcase is empty, thus there is no book at any position at any shelf.The bookcase consists of n shelves, and each shelf has exactly m positions for books at it. Alina enumerates shelves by integers from 1 to n and positions at shelves — from 1 to m. Initially the bookcase is empty, thus there is no book at any position at any shelf in it.Alina wrote down q operations, which will be consecutively applied to the bookcase. Each of the operations has one of four types: 1 i j — Place a book at position j at shelf i if there is no book at it. 2 i j — Remove the book from position j at shelf i if there is a book at it. 3 i — Invert book placing at shelf i. This means that from every position at shelf i which has a book at it, the book should be removed, and at every position at shelf i which has not book at it, a book should be placed. 4 k — Return the books in the bookcase in a state they were after applying k-th operation. In particular, k = 0 means that the bookcase should be in initial state, thus every book in the bookcase should be removed from its position.After applying each of operation Alina is interested in the number of books in the bookcase. Alina got 'A' in the school and had no problem finding this values. Will you do so?",[]282"This is the hard version of the problem. You can find the easy version in the Div. 2 contest. Both versions only differ in the number of times you can ask your friend to taste coffee.This is an interactive problem.You're considering moving to another city, where one of your friends already lives. There are $$$n$$$ cafés in this city, where $$$n$$$ is a power of two. The $$$i$$$-th café produces a single variety of coffee $$$a_i$$$. As you're a coffee-lover, before deciding to move or not, you want to know the number $$$d$$$ of distinct varieties of coffees produced in this city.You don't know the values $$$a_1, \ldots, a_n$$$. Fortunately, your friend has a memory of size $$$k$$$, where $$$k$$$ is a power of two.Once per day, you can ask him to taste a cup of coffee produced by the café $$$c$$$, and he will tell you if he tasted a similar coffee during the last $$$k$$$ days.You can also ask him to take a medication that will reset his memory. He will forget all previous cups of coffee tasted. You can reset his memory at most $$$30\ 000$$$ times.More formally, the memory of your friend is a queue $$$S$$$. Doing a query on café $$$c$$$ will:   Tell you if $$$a_c$$$ is in $$$S$$$;  Add $$$a_c$$$ at the back of $$$S$$$;  If $$$|S| > k$$$, pop the front element of $$$S$$$. Doing a reset request will pop all elements out of $$$S$$$.Your friend can taste at most $$$\dfrac{3n^2}{2k}$$$ cups of coffee in total. Find the diversity $$$d$$$ (number of distinct values in the array $$$a$$$).Note that asking your friend to reset his memory does not count towards the number of times you ask your friend to taste a cup of coffee.In some test cases the behavior of the interactor is adaptive. It means that the array $$$a$$$ may be not fixed before the start of the interaction and may depend on your queries. It is guaranteed that at any moment of the interaction, there is at least one array $$$a$$$ consistent with all the answers given so far.",['graphs']283"Ashish has two strings $$$a$$$ and $$$b$$$, each of length $$$n$$$, and an integer $$$k$$$. The strings only contain lowercase English letters.He wants to convert string $$$a$$$ into string $$$b$$$ by performing some (possibly zero) operations on $$$a$$$.In one move, he can either   choose an index $$$i$$$ ($$$1 \leq i\leq n-1$$$) and swap $$$a_i$$$ and $$$a_{i+1}$$$, or  choose an index $$$i$$$ ($$$1 \leq i \leq n-k+1$$$) and if $$$a_i, a_{i+1}, \ldots, a_{i+k-1}$$$ are all equal to some character $$$c$$$ ($$$c \neq$$$ 'z'), replace each one with the next character $$$(c+1)$$$, that is, 'a' is replaced by 'b', 'b' is replaced by 'c' and so on. Note that he can perform any number of operations, and the operations can only be performed on string $$$a$$$. Help Ashish determine if it is possible to convert string $$$a$$$ into $$$b$$$ after performing some (possibly zero) operations on it.",['strings']284"After waking up at hh:mm, Andrew realised that he had forgotten to feed his only cat for yet another time (guess why there's only one cat). The cat's current hunger level is H points, moreover each minute without food increases his hunger by D points.At any time Andrew can visit the store where tasty buns are sold (you can assume that is doesn't take time to get to the store and back). One such bun costs C roubles and decreases hunger by N points. Since the demand for bakery drops heavily in the evening, there is a special 20% discount for buns starting from 20:00 (note that the cost might become rational). Of course, buns cannot be sold by parts.Determine the minimum amount of money Andrew has to spend in order to feed his cat. The cat is considered fed if its hunger level is less than or equal to zero.",['math']285"Riley is a very bad boy, but at the same time, he is a yo-yo master. So, he decided to use his yo-yo skills to annoy his friend Anton.Anton's room can be represented as a grid with $$$n$$$ rows and $$$m$$$ columns. Let $$$(i, j)$$$ denote the cell in row $$$i$$$ and column $$$j$$$. Anton is currently standing at position $$$(i, j)$$$ in his room. To annoy Anton, Riley decided to throw exactly two yo-yos in cells of the room (they can be in the same cell).Because Anton doesn't like yo-yos thrown on the floor, he has to pick up both of them and return back to the initial position. The distance travelled by Anton is the shortest path that goes through the positions of both yo-yos and returns back to $$$(i, j)$$$ by travelling only to adjacent by side cells. That is, if he is in cell $$$(x, y)$$$ then he can travel to the cells $$$(x + 1, y)$$$, $$$(x - 1, y)$$$, $$$(x, y + 1)$$$ and $$$(x, y - 1)$$$ in one step (if a cell with those coordinates exists).Riley is wondering where he should throw these two yo-yos so that the distance travelled by Anton is maximized. But because he is very busy, he asked you to tell him.",['math']286"This problem is interactive.You should guess hidden number $$$x$$$ which is between $$$1$$$ and $$$M = 10004205361450474$$$, inclusive.You could use up to $$$5$$$ queries.In each query, you can output an increasing sequence of $$$k \leq x$$$ integers, each between $$$1$$$ and $$$M$$$, inclusive, and you will obtain one of the following as an answer:  either the hidden number belongs to your query sequence, in this case you immediately win;  or you will be given where the hidden number is located with respect to your query sequence, that is, either it is less than all numbers from the sequence, greater than all numbers from the sequence, or you will be given such an $$$i$$$ that the hidden number $$$x$$$ is between the $$$i$$$-th and the $$$(i+1)$$$-st numbers of your sequence. See the interaction section for clarity.Be aware that the interactor is adaptive, i.e. the hidden number can depend on queries the solution makes. However, it is guaranteed that for any solution the interactor works non-distinguishable from the situation when the hidden number is fixed beforehand.Hacks are allowed only with fixed hidden number. A hack is represented by a single integer between $$$1$$$ and $$$M$$$. In all pretests the hidden number is fixed as well.",[]287"You are given a sequence of positive integers a1, a2, ..., an. While possible, you perform the following operation: find a pair of equal consecutive elements. If there are more than one such pair, find the leftmost (with the smallest indices of elements). If the two integers are equal to x, delete both and insert a single integer x + 1 on their place. This way the number of elements in the sequence is decreased by 1 on each step. You stop performing the operation when there is no pair of equal consecutive elements.For example, if the initial sequence is [5, 2, 1, 1, 2, 2], then after the first operation you get [5, 2, 2, 2, 2], after the second — [5, 3, 2, 2], after the third — [5, 3, 3], and finally after the fourth you get [5, 4]. After that there are no equal consecutive elements left in the sequence, so you stop the process.Determine the final sequence after you stop performing the operation.",[]288"Pavel loves grid mazes. A grid maze is an n × m rectangle maze where each cell is either empty, or is a wall. You can go from one cell to another only if both cells are empty and have a common side.Pavel drew a grid maze with all empty cells forming a connected area. That is, you can go from any empty cell to any other one. Pavel doesn't like it when his maze has too little walls. He wants to turn exactly k empty cells into walls so that all the remaining cells still formed a connected area. Help him.",[]289"This is an interactive problem!Nastia has a hidden permutation $$$p$$$ of length $$$n$$$ consisting of integers from $$$1$$$ to $$$n$$$. You, for some reason, want to figure out the permutation. To do that, you can give her an integer $$$t$$$ ($$$1 \le t \le 2$$$), two different indices $$$i$$$ and $$$j$$$ ($$$1 \le i, j \le n$$$, $$$i \neq j$$$), and an integer $$$x$$$ ($$$1 \le x \le n - 1$$$). Depending on $$$t$$$, she will answer:   $$$t = 1$$$: $$$\max{(\min{(x, p_i)}, \min{(x + 1, p_j)})}$$$;  $$$t = 2$$$: $$$\min{(\max{(x, p_i)}, \max{(x + 1, p_j)})}$$$. You can ask Nastia at most $$$\lfloor \frac {3 \cdot n} { 2} \rfloor + 30$$$ times. It is guaranteed that she will not change her permutation depending on your queries. Can you guess the permutation?",[]290"There are $$$n$$$ points on a coordinate axis $$$OX$$$. The $$$i$$$-th point is located at the integer point $$$x_i$$$ and has a speed $$$v_i$$$. It is guaranteed that no two points occupy the same coordinate. All $$$n$$$ points move with the constant speed, the coordinate of the $$$i$$$-th point at the moment $$$t$$$ ($$$t$$$ can be non-integer) is calculated as $$$x_i + t \cdot v_i$$$.Consider two points $$$i$$$ and $$$j$$$. Let $$$d(i, j)$$$ be the minimum possible distance between these two points over any possible moments of time (even non-integer). It means that if two points $$$i$$$ and $$$j$$$ coincide at some moment, the value $$$d(i, j)$$$ will be $$$0$$$.Your task is to calculate the value $$$\sum\limits_{1 \le i < j \le n}$$$ $$$d(i, j)$$$ (the sum of minimum distances over all pairs of points).",[]291"PizzaForces is Petya's favorite pizzeria. PizzaForces makes and sells pizzas of three sizes: small pizzas consist of $$$6$$$ slices, medium ones consist of $$$8$$$ slices, and large pizzas consist of $$$10$$$ slices each. Baking them takes $$$15$$$, $$$20$$$ and $$$25$$$ minutes, respectively.Petya's birthday is today, and $$$n$$$ of his friends will come, so he decided to make an order from his favorite pizzeria. Petya wants to order so much pizza that each of his friends gets at least one slice of pizza. The cooking time of the order is the total baking time of all the pizzas in the order.Your task is to determine the minimum number of minutes that is needed to make pizzas containing at least $$$n$$$ slices in total. For example:   if $$$12$$$ friends come to Petya's birthday, he has to order pizzas containing at least $$$12$$$ slices in total. He can order two small pizzas, containing exactly $$$12$$$ slices, and the time to bake them is $$$30$$$ minutes;  if $$$15$$$ friends come to Petya's birthday, he has to order pizzas containing at least $$$15$$$ slices in total. He can order a small pizza and a large pizza, containing $$$16$$$ slices, and the time to bake them is $$$40$$$ minutes;  if $$$300$$$ friends come to Petya's birthday, he has to order pizzas containing at least $$$300$$$ slices in total. He can order $$$15$$$ small pizzas, $$$10$$$ medium pizzas and $$$13$$$ large pizzas, in total they contain $$$15 \cdot 6 + 10 \cdot 8 + 13 \cdot 10 = 300$$$ slices, and the total time to bake them is $$$15 \cdot 15 + 10 \cdot 20 + 13 \cdot 25 = 750$$$ minutes;  if only one friend comes to Petya's birthday, he can order a small pizza, and the time to bake it is $$$15$$$ minutes. ",['math']292"Iahub got lost in a very big desert. The desert can be represented as a n × n square matrix, where each cell is a zone of the desert. The cell (i, j) represents the cell at row i and column j (1 ≤ i, j ≤ n). Iahub can go from one cell (i, j) only down or right, that is to cells (i + 1, j) or (i, j + 1). Also, there are m cells that are occupied by volcanoes, which Iahub cannot enter. Iahub is initially at cell (1, 1) and he needs to travel to cell (n, n). Knowing that Iahub needs 1 second to travel from one cell to another, find the minimum time in which he can arrive in cell (n, n).",[]293"""We've tried solitary confinement, waterboarding and listening to Just In Beaver, to no avail. We need something extreme.""""Little Alena got an array as a birthday present...""The array b of length n is obtained from the array a of length n and two integers l and r (l ≤ r) using the following procedure:b1 = b2 = b3 = b4 = 0.For all 5 ≤ i ≤ n:   bi = 0 if ai, ai - 1, ai - 2, ai - 3, ai - 4 > r and bi - 1 = bi - 2 = bi - 3 = bi - 4 = 1  bi = 1 if ai, ai - 1, ai - 2, ai - 3, ai - 4 < l and bi - 1 = bi - 2 = bi - 3 = bi - 4 = 0  bi = bi - 1 otherwise You are given arrays a and b' of the same length. Find two integers l and r (l ≤ r), such that applying the algorithm described above will yield an array b equal to b'.It's guaranteed that the answer exists.",[]294"Catherine received an array of integers as a gift for March 8. Eventually she grew bored with it, and she started calculated various useless characteristics for it. She succeeded to do it for each one she came up with. But when she came up with another one — xor of all pairwise sums of elements in the array, she realized that she couldn't compute it for a very large array, thus she asked for your help. Can you do it? Formally, you need to compute$$$$$$ (a_1 + a_2) \oplus (a_1 + a_3) \oplus \ldots \oplus (a_1 + a_n) \\ \oplus (a_2 + a_3) \oplus \ldots \oplus (a_2 + a_n) \\ \ldots \\ \oplus (a_{n-1} + a_n) \\ $$$$$$Here $$$x \oplus y$$$ is a bitwise XOR operation (i.e. $$$x$$$ ^ $$$y$$$ in many modern programming languages). You can read about it in Wikipedia: https://en.wikipedia.org/wiki/Exclusive_or#Bitwise_operation.",['math']295"Skier rides on a snowy field. Its movements can be described by a string of characters 'S', 'N', 'W', 'E' (which correspond to $$$1$$$ meter movement in the south, north, west or east direction respectively).It is known that if he moves along a previously unvisited segment of a path (i.e. this segment of the path is visited the first time), then the time of such movement is $$$5$$$ seconds. If he rolls along previously visited segment of a path (i.e., this segment of the path has been covered by his path before), then it takes $$$1$$$ second.Find the skier's time to roll all the path.",[]296"You are given an array of $$$n$$$ integers $$$a_1, a_2, \dots, a_n$$$You can apply the following operation an arbitrary number of times:   select an index $$$i$$$ ($$$1 \le i \le n$$$) and replace the value of the element $$$a_i$$$ with the value $$$a_i + (a_i \bmod 10)$$$, where $$$a_i \bmod 10$$$ is the remainder of the integer dividing $$$a_i$$$ by $$$10$$$. For a single index (value $$$i$$$), this operation can be applied multiple times. If the operation is applied repeatedly to the same index, then the current value of $$$a_i$$$ is taken into account each time. For example, if $$$a_i=47$$$ then after the first operation we get $$$a_i=47+7=54$$$, and after the second operation we get $$$a_i=54+4=58$$$.Check if it is possible to make all array elements equal by applying multiple (possibly zero) operations.For example, you have an array $$$[6, 11]$$$.   Let's apply this operation to the first element of the array. Let's replace $$$a_1 = 6$$$ with $$$a_1 + (a_1 \bmod 10) = 6 + (6 \bmod 10) = 6 + 6 = 12$$$. We get the array $$$[12, 11]$$$.  Then apply this operation to the second element of the array. Let's replace $$$a_2 = 11$$$ with $$$a_2 + (a_2 \bmod 10) = 11 + (11 \bmod 10) = 11 + 1 = 12$$$. We get the array $$$[12, 12]$$$. Thus, by applying $$$2$$$ operations, you can make all elements of an array equal.","['math', 'number theory']"297"Phoenix has a string $$$s$$$ consisting of lowercase Latin letters. He wants to distribute all the letters of his string into $$$k$$$ non-empty strings $$$a_1, a_2, \dots, a_k$$$ such that every letter of $$$s$$$ goes to exactly one of the strings $$$a_i$$$. The strings $$$a_i$$$ do not need to be substrings of $$$s$$$. Phoenix can distribute letters of $$$s$$$ and rearrange the letters within each string $$$a_i$$$ however he wants.For example, if $$$s = $$$ baba and $$$k=2$$$, Phoenix may distribute the letters of his string in many ways, such as:   ba and ba  a and abb  ab and ab  aa and bb But these ways are invalid:   baa and ba  b and ba  baba and empty string ($$$a_i$$$ should be non-empty) Phoenix wants to distribute the letters of his string $$$s$$$ into $$$k$$$ strings $$$a_1, a_2, \dots, a_k$$$ to minimize the lexicographically maximum string among them, i. e. minimize $$$max(a_1, a_2, \dots, a_k)$$$. Help him find the optimal distribution and print the minimal possible value of $$$max(a_1, a_2, \dots, a_k)$$$.String $$$x$$$ is lexicographically less than string $$$y$$$ if either $$$x$$$ is a prefix of $$$y$$$ and $$$x \ne y$$$, or there exists an index $$$i$$$ ($$$1 \le i \le min(|x|, |y|))$$$ such that $$$x_i$$$ < $$$y_i$$$ and for every $$$j$$$ $$$(1 \le j < i)$$$ $$$x_j = y_j$$$. Here $$$|x|$$$ denotes the length of the string $$$x$$$.",['strings']298"Suppose that you are in a campus and have to go for classes day by day. As you may see, when you hurry to a classroom, you surprisingly find that many seats there are already occupied. Today you and your friends went for class, and found out that some of the seats were occupied.The classroom contains $$$n$$$ rows of seats and there are $$$m$$$ seats in each row. Then the classroom can be represented as an $$$n \times m$$$ matrix. The character '.' represents an empty seat, while '*' means that the seat is occupied. You need to find $$$k$$$ consecutive empty seats in the same row or column and arrange those seats for you and your friends. Your task is to find the number of ways to arrange the seats. Two ways are considered different if sets of places that students occupy differs.",[]299"Monocarp has drawn a tree (an undirected connected acyclic graph) and then has given each vertex an index. All indices are distinct numbers from $$$1$$$ to $$$n$$$. For every edge $$$e$$$ of this tree, Monocarp has written two numbers: the maximum indices of the vertices of the two components formed if the edge $$$e$$$ (and only this edge) is erased from the tree.Monocarp has given you a list of $$$n - 1$$$ pairs of numbers. He wants you to provide an example of a tree that will produce the said list if this tree exists. If such tree does not exist, say so.",['graphs']300"There are $$$n$$$ lanterns in a row. The lantern $$$i$$$ is placed in position $$$i$$$ and has power equal to $$$p_i$$$.Each lantern can be directed to illuminate either some lanterns to the left or some lanterns to the right. If the $$$i$$$-th lantern is turned to the left, it illuminates all such lanterns $$$j$$$ that $$$j \in [i - p_i, i - 1]$$$. Similarly, if it is turned to the right, it illuminates all such lanterns $$$j$$$ that $$$j \in [i + 1, i + p_i]$$$.Your goal is to choose a direction for each lantern so each lantern is illuminated by at least one other lantern, or report that it is impossible.",[]301"Zookeeper is buying a carton of fruit to feed his pet wabbit. The fruits are a sequence of apples and oranges, which is represented by a binary string $$$s_1s_2\ldots s_n$$$ of length $$$n$$$. $$$1$$$ represents an apple and $$$0$$$ represents an orange.Since wabbit is allergic to eating oranges, Zookeeper would like to find the longest contiguous sequence of apples. Let $$$f(l,r)$$$ be the longest contiguous sequence of apples in the substring $$$s_{l}s_{l+1}\ldots s_{r}$$$. Help Zookeeper find $$$\sum_{l=1}^{n} \sum_{r=l}^{n} f(l,r)$$$, or the sum of $$$f$$$ across all substrings.",[]302"You are given a string $$$s$$$ of length $$$n$$$. Each character is either one of the first $$$k$$$ lowercase Latin letters or a question mark.You are asked to replace every question mark with one of the first $$$k$$$ lowercase Latin letters in such a way that the following value is maximized.Let $$$f_i$$$ be the maximum length substring of string $$$s$$$, which consists entirely of the $$$i$$$-th Latin letter. A substring of a string is a contiguous subsequence of that string. If the $$$i$$$-th letter doesn't appear in a string, then $$$f_i$$$ is equal to $$$0$$$.The value of a string $$$s$$$ is the minimum value among $$$f_i$$$ for all $$$i$$$ from $$$1$$$ to $$$k$$$.What is the maximum value the string can have?",['strings']303"A group of $$$n$$$ friends decide to go to a restaurant. Each of the friends plans to order meals for $$$x_i$$$ burles and has a total of $$$y_i$$$ burles ($$$1 \le i \le n$$$). The friends decide to split their visit to the restaurant into several days. Each day, some group of at least two friends goes to the restaurant. Each of the friends visits the restaurant no more than once (that is, these groups do not intersect). These groups must satisfy the condition that the total budget of each group must be not less than the amount of burles that the friends in the group are going to spend at the restaurant. In other words, the sum of all $$$x_i$$$ values in the group must not exceed the sum of $$$y_i$$$ values in the group.What is the maximum number of days friends can visit the restaurant?For example, let there be $$$n = 6$$$ friends for whom $$$x$$$ = [$$$8, 3, 9, 2, 4, 5$$$] and $$$y$$$ = [$$$5, 3, 1, 4, 5, 10$$$]. Then:   first and sixth friends can go to the restaurant on the first day. They will spend $$$8+5=13$$$ burles at the restaurant, and their total budget is $$$5+10=15$$$ burles. Since $$$15 \ge 13$$$, they can actually form a group.  friends with indices $$$2, 4, 5$$$ can form a second group. They will spend $$$3+2+4=9$$$ burles at the restaurant, and their total budget will be $$$3+4+5=12$$$ burles ($$$12 \ge 9$$$). It can be shown that they will not be able to form more groups so that each group has at least two friends and each group can pay the bill.So, the maximum number of groups the friends can split into is $$$2$$$. Friends will visit the restaurant for a maximum of two days. Note that the $$$3$$$-rd friend will not visit the restaurant at all.Output the maximum number of days the friends can visit the restaurant for given $$$n$$$, $$$x$$$ and $$$y$$$.",[]304"Hyakugoku has just retired from being the resident deity of the South Black Snail Temple in order to pursue her dream of becoming a cartoonist. She spent six months in that temple just playing ""Cat's Cradle"" so now she wants to try a different game — ""Snakes and Ladders"". Unfortunately, she already killed all the snakes, so there are only ladders left now. The game is played on a $$$10 \times 10$$$ board as follows:  At the beginning of the game, the player is at the bottom left square.  The objective of the game is for the player to reach the Goal (the top left square) by following the path and climbing vertical ladders. Once the player reaches the Goal, the game ends.  The path is as follows: if a square is not the end of its row, it leads to the square next to it along the direction of its row; if a square is the end of its row, it leads to the square above it. The direction of a row is determined as follows: the direction of the bottom row is to the right; the direction of any other row is opposite the direction of the row below it. See Notes section for visualization of path.  During each turn, the player rolls a standard six-sided dice. Suppose that the number shown on the dice is $$$r$$$. If the Goal is less than $$$r$$$ squares away on the path, the player doesn't move (but the turn is performed). Otherwise, the player advances exactly $$$r$$$ squares along the path and then stops. If the player stops on a square with the bottom of a ladder, the player chooses whether or not to climb up that ladder. If she chooses not to climb, then she stays in that square for the beginning of the next turn.  Some squares have a ladder in them. Ladders are only placed vertically — each one leads to the same square of some of the upper rows. In order for the player to climb up a ladder, after rolling the dice, she must stop at the square containing the bottom of the ladder. After using the ladder, the player will end up in the square containing the top of the ladder. She cannot leave the ladder in the middle of climbing. And if the square containing the top of the ladder also contains the bottom of another ladder, she is not allowed to use that second ladder.  The numbers on the faces of the dice are 1, 2, 3, 4, 5, and 6, with each number having the same probability of being shown. Please note that:      it is possible for ladders to overlap, but the player cannot switch to the other ladder while in the middle of climbing the first one;     it is possible for ladders to go straight to the top row, but not any higher;     it is possible for two ladders to lead to the same tile;     it is possible for a ladder to lead to a tile that also has a ladder, but the player will not be able to use that second ladder if she uses the first one;     the player can only climb up ladders, not climb down. Hyakugoku wants to finish the game as soon as possible. Thus, on each turn she chooses whether to climb the ladder or not optimally. Help her to determine the minimum expected number of turns the game will take.",['probabilities']305"Vanya wants to minimize a tree. He can perform the following operation multiple times: choose a vertex v, and two disjoint (except for v) paths of equal length a0 = v, a1, ..., ak, and b0 = v, b1, ..., bk. Additionally, vertices a1, ..., ak, b1, ..., bk must not have any neighbours in the tree other than adjacent vertices of corresponding paths. After that, one of the paths may be merged into the other, that is, the vertices b1, ..., bk can be effectively erased:  Help Vanya determine if it possible to make the tree into a path via a sequence of described operations, and if the answer is positive, also determine the shortest length of such path.",['trees']306"John Doe started thinking about graphs. After some thought he decided that he wants to paint an undirected graph, containing exactly k cycles of length 3. A cycle of length 3 is an unordered group of three distinct graph vertices a, b and c, such that each pair of them is connected by a graph edge. John has been painting for long, but he has not been a success. Help him find such graph. Note that the number of vertices there shouldn't exceed 100, or else John will have problems painting it.",['graphs']307"Sengoku still remembers the mysterious ""colourful meteoroids"" she discovered with Lala-chan when they were little. In particular, one of the nights impressed her deeply, giving her the illusion that all her fancies would be realized.On that night, Sengoku constructed a permutation p1, p2, ..., pn of integers from 1 to n inclusive, with each integer representing a colour, wishing for the colours to see in the coming meteor outburst. Two incredible outbursts then arrived, each with n meteorids, colours of which being integer sequences a1, a2, ..., an and b1, b2, ..., bn respectively. Meteoroids' colours were also between 1 and n inclusive, and the two sequences were not identical, that is, at least one i (1 ≤ i ≤ n) exists, such that ai ≠ bi holds.Well, she almost had it all — each of the sequences a and b matched exactly n - 1 elements in Sengoku's permutation. In other words, there is exactly one i (1 ≤ i ≤ n) such that ai ≠ pi, and exactly one j (1 ≤ j ≤ n) such that bj ≠ pj.For now, Sengoku is able to recover the actual colour sequences a and b through astronomical records, but her wishes have been long forgotten. You are to reconstruct any possible permutation Sengoku could have had on that night.",[]308"One day, you are accepted as being Dr. Chanek's assistant. The first task given by Dr. Chanek to you is to take care and store his magical stones.Dr. Chanek has $$$N$$$ magical stones with $$$N$$$ being an even number. Those magical stones are numbered from $$$1$$$ to $$$N$$$. Magical stone $$$i$$$ has a strength of $$$A_i$$$. A magical stone can be painted with two colours, namely the colour black or the colour white. You are tasked to paint the magical stones with the colour black or white and store the magical stones into a magic box with a magic coefficient $$$Z$$$ ($$$0 \leq Z \leq 2$$$). The painting of the magical stones must be done in a way such that there are $$$\frac{N}{2}$$$ black magical stones and $$$\frac{N}{2}$$$ white magical stones.Define $$$\text{concat}(x, y)$$$ for two integers $$$x$$$ and $$$y$$$ as the result of concatenating the digits of $$$x$$$ to the left of $$$y$$$ in their decimal representation without changing the order. As an example, $$$\text{concat}(10, 24)$$$ will result in $$$1024$$$.For a magic box with a magic coefficient $$$Z$$$, magical stone $$$i$$$ will react with magical stone $$$j$$$ if the colours of both stones are different and $$$\text{concat}(A_i, A_j) \times \text{concat}(A_j, A_i) + A_i \times A_j \equiv Z \mod 3$$$. A magical stone that is reacting will be very hot and dangerous. Because of that, you must colour the magical stones and determine the magic coefficient $$$Z$$$ of the magic box in a way such that there is no magical stone that reacts, or report if it is impossible.",['math']309"Little Petya often travels to his grandmother in the countryside. The grandmother has a large garden, which can be represented as a rectangle 1 × n in size, when viewed from above. This rectangle is divided into n equal square sections. The garden is very unusual as each of the square sections possesses its own fixed height and due to the newest irrigation system we can create artificial rain above each section.Creating artificial rain is an expensive operation. That's why we limit ourselves to creating the artificial rain only above one section. At that, the water from each watered section will flow into its neighbouring sections if their height does not exceed the height of the section. That is, for example, the garden can be represented by a 1 × 5 rectangle, where the section heights are equal to 4, 2, 3, 3, 2. Then if we create an artificial rain over any of the sections with the height of 3, the water will flow over all the sections, except the ones with the height of 4. See the illustration of this example at the picture:  As Petya is keen on programming, he decided to find such a section that if we create artificial rain above it, the number of watered sections will be maximal. Help him. ",[]310"You are given $$$n$$$ numbers $$$a_1, a_2, \dots, a_n$$$. With a cost of one coin you can perform the following operation:Choose one of these numbers and add or subtract $$$1$$$ from it.In particular, we can apply this operation to the same number several times.We want to make the product of all these numbers equal to $$$1$$$, in other words, we want $$$a_1 \cdot a_2$$$ $$$\dots$$$ $$$\cdot a_n = 1$$$. For example, for $$$n = 3$$$ and numbers $$$[1, -3, 0]$$$ we can make product equal to $$$1$$$ in $$$3$$$ coins: add $$$1$$$ to second element, add $$$1$$$ to second element again, subtract $$$1$$$ from third element, so that array becomes $$$[1, -1, -1]$$$. And $$$1\cdot (-1) \cdot (-1) = 1$$$.What is the minimum cost we will have to pay to do that?",[]311"A boy Bob likes to draw. Not long ago he bought a rectangular graph (checked) sheet with n rows and m columns. Bob shaded some of the squares on the sheet. Having seen his masterpiece, he decided to share it with his elder brother, who lives in Flatland. Now Bob has to send his picture by post, but because of the world economic crisis and high oil prices, he wants to send his creation, but to spend as little money as possible. For each sent square of paper (no matter whether it is shaded or not) Bob has to pay 3.14 burles. Please, help Bob cut out of his masterpiece a rectangle of the minimum cost, that will contain all the shaded squares. The rectangle's sides should be parallel to the sheet's sides.",[]312"You are given a positive integer $$$n$$$. You have to find $$$4$$$ positive integers $$$a, b, c, d$$$ such that  $$$a + b + c + d = n$$$, and $$$\gcd(a, b) = \operatorname{lcm}(c, d)$$$.If there are several possible answers you can output any of them. It is possible to show that the answer always exists.In this problem $$$\gcd(a, b)$$$ denotes the greatest common divisor of $$$a$$$ and $$$b$$$, and $$$\operatorname{lcm}(c, d)$$$ denotes the least common multiple of $$$c$$$ and $$$d$$$.",['math']313"You are given an array $$$a$$$ of $$$n$$$ integers.You want to make all elements of $$$a$$$ equal to zero by doing the following operation exactly three times:  Select a segment, for each number in this segment we can add a multiple of $$$len$$$ to it, where $$$len$$$ is the length of this segment (added integers can be different). It can be proven that it is always possible to make all elements of $$$a$$$ equal to zero.","['math', 'number theory']"314"Connected undirected weighted graph without self-loops and multiple edges is given. Graph contains n vertices and m edges.For each edge (u, v) find the minimal possible weight of the spanning tree that contains the edge (u, v).The weight of the spanning tree is the sum of weights of all edges included in spanning tree.","['graphs', 'trees']"315"Mishka got an integer array $$$a$$$ of length $$$n$$$ as a birthday present (what a surprise!).Mishka doesn't like this present and wants to change it somehow. He has invented an algorithm and called it ""Mishka's Adjacent Replacements Algorithm"". This algorithm can be represented as a sequence of steps:  Replace each occurrence of $$$1$$$ in the array $$$a$$$ with $$$2$$$;  Replace each occurrence of $$$2$$$ in the array $$$a$$$ with $$$1$$$;  Replace each occurrence of $$$3$$$ in the array $$$a$$$ with $$$4$$$;  Replace each occurrence of $$$4$$$ in the array $$$a$$$ with $$$3$$$;  Replace each occurrence of $$$5$$$ in the array $$$a$$$ with $$$6$$$;  Replace each occurrence of $$$6$$$ in the array $$$a$$$ with $$$5$$$;  $$$\dots$$$  Replace each occurrence of $$$10^9 - 1$$$ in the array $$$a$$$ with $$$10^9$$$;  Replace each occurrence of $$$10^9$$$ in the array $$$a$$$ with $$$10^9 - 1$$$. Note that the dots in the middle of this algorithm mean that Mishka applies these replacements for each pair of adjacent integers ($$$2i - 1, 2i$$$) for each $$$i \in\{1, 2, \ldots, 5 \cdot 10^8\}$$$ as described above.For example, for the array $$$a = [1, 2, 4, 5, 10]$$$, the following sequence of arrays represents the algorithm: $$$[1, 2, 4, 5, 10]$$$ $$$\rightarrow$$$ (replace all occurrences of $$$1$$$ with $$$2$$$) $$$\rightarrow$$$ $$$[2, 2, 4, 5, 10]$$$ $$$\rightarrow$$$ (replace all occurrences of $$$2$$$ with $$$1$$$) $$$\rightarrow$$$ $$$[1, 1, 4, 5, 10]$$$ $$$\rightarrow$$$ (replace all occurrences of $$$3$$$ with $$$4$$$) $$$\rightarrow$$$ $$$[1, 1, 4, 5, 10]$$$ $$$\rightarrow$$$ (replace all occurrences of $$$4$$$ with $$$3$$$) $$$\rightarrow$$$ $$$[1, 1, 3, 5, 10]$$$ $$$\rightarrow$$$ (replace all occurrences of $$$5$$$ with $$$6$$$) $$$\rightarrow$$$ $$$[1, 1, 3, 6, 10]$$$ $$$\rightarrow$$$ (replace all occurrences of $$$6$$$ with $$$5$$$) $$$\rightarrow$$$ $$$[1, 1, 3, 5, 10]$$$ $$$\rightarrow$$$ $$$\dots$$$ $$$\rightarrow$$$ $$$[1, 1, 3, 5, 10]$$$ $$$\rightarrow$$$ (replace all occurrences of $$$10$$$ with $$$9$$$) $$$\rightarrow$$$ $$$[1, 1, 3, 5, 9]$$$. The later steps of the algorithm do not change the array.Mishka is very lazy and he doesn't want to apply these changes by himself. But he is very interested in their result. Help him find it.",[]316"You are given a matrix with $$$n$$$ rows (numbered from $$$1$$$ to $$$n$$$) and $$$m$$$ columns (numbered from $$$1$$$ to $$$m$$$). A number $$$a_{i, j}$$$ is written in the cell belonging to the $$$i$$$-th row and the $$$j$$$-th column, each number is either $$$0$$$ or $$$1$$$.A chip is initially in the cell $$$(1, 1)$$$, and it will be moved to the cell $$$(n, m)$$$. During each move, it either moves to the next cell in the current row, or in the current column (if the current cell is $$$(x, y)$$$, then after the move it can be either $$$(x + 1, y)$$$ or $$$(x, y + 1)$$$). The chip cannot leave the matrix.Consider each path of the chip from $$$(1, 1)$$$ to $$$(n, m)$$$. A path is called palindromic if the number in the first cell is equal to the number in the last cell, the number in the second cell is equal to the number in the second-to-last cell, and so on.Your goal is to change the values in the minimum number of cells so that every path is palindromic.",['math']317"Petya once wrote a sad love song and shared it to Vasya. The song is a string consisting of lowercase English letters. Vasya made up $$$q$$$ questions about this song. Each question is about a subsegment of the song starting from the $$$l$$$-th letter to the $$$r$$$-th letter. Vasya considers a substring made up from characters on this segment and repeats each letter in the subsegment $$$k$$$ times, where $$$k$$$ is the index of the corresponding letter in the alphabet. For example, if the question is about the substring ""abbcb"", then Vasya repeats letter 'a' once, each of the letters 'b' twice, letter 'c"" three times, so that the resulting string is ""abbbbcccbb"", its length is $$$10$$$. Vasya is interested about the length of the resulting string.Help Petya find the length of each string obtained by Vasya.",['strings']318"One day, as Sherlock Holmes was tracking down one very important criminal, he found a wonderful painting on the wall. This wall could be represented as a plane. The painting had several concentric circles that divided the wall into several parts. Some parts were painted red and all the other were painted blue. Besides, any two neighboring parts were painted different colors, that is, the red and the blue color were alternating, i. e. followed one after the other. The outer area of the wall (the area that lied outside all circles) was painted blue. Help Sherlock Holmes determine the total area of red parts of the wall.Let us remind you that two circles are called concentric if their centers coincide. Several circles are called concentric if any two of them are concentric.",['geometry']319"Valera is a collector. Once he wanted to expand his collection with exactly one antique item.Valera knows n sellers of antiques, the i-th of them auctioned ki items. Currently the auction price of the j-th object of the i-th seller is sij. Valera gets on well with each of the n sellers. He is perfectly sure that if he outbids the current price of one of the items in the auction (in other words, offers the seller the money that is strictly greater than the current price of the item at the auction), the seller of the object will immediately sign a contract with him.Unfortunately, Valera has only v units of money. Help him to determine which of the n sellers he can make a deal with.",[]320"On the well-known testing system MathForces, a draw of $$$n$$$ rating units is arranged. The rating will be distributed according to the following algorithm: if $$$k$$$ participants take part in this event, then the $$$n$$$ rating is evenly distributed between them and rounded to the nearest lower integer, At the end of the drawing, an unused rating may remain — it is not given to any of the participants.For example, if $$$n = 5$$$ and $$$k = 3$$$, then each participant will recieve an $$$1$$$ rating unit, and also $$$2$$$ rating units will remain unused. If $$$n = 5$$$, and $$$k = 6$$$, then none of the participants will increase their rating.Vasya participates in this rating draw but does not have information on the total number of participants in this event. Therefore, he wants to know what different values of the rating increment are possible to get as a result of this draw and asks you for help.For example, if $$$n=5$$$, then the answer is equal to the sequence $$$0, 1, 2, 5$$$. Each of the sequence values (and only them) can be obtained as $$$\lfloor n/k \rfloor$$$ for some positive integer $$$k$$$ (where $$$\lfloor x \rfloor$$$ is the value of $$$x$$$ rounded down): $$$0 = \lfloor 5/7 \rfloor$$$, $$$1 = \lfloor 5/5 \rfloor$$$, $$$2 = \lfloor 5/2 \rfloor$$$, $$$5 = \lfloor 5/1 \rfloor$$$.Write a program that, for a given $$$n$$$, finds a sequence of all possible rating increments.","['math', 'number theory']"321"Kuznecov likes art, poetry, and music. And strings consisting of lowercase English letters.Recently, Kuznecov has found two strings, $$$a$$$ and $$$b$$$, of lengths $$$n$$$ and $$$m$$$ respectively. They consist of lowercase English letters and no character is contained in both strings. Let another string $$$c$$$ be initially empty. Kuznecov can do the following two types of operations:  Choose any character from the string $$$a$$$, remove it from $$$a$$$, and add it to the end of $$$c$$$.  Choose any character from the string $$$b$$$, remove it from $$$b$$$, and add it to the end of $$$c$$$. But, he can not do more than $$$k$$$ operations of the same type in a row. He must perform operations until either $$$a$$$ or $$$b$$$ becomes empty. What is the lexicographically smallest possible value of $$$c$$$ after he finishes?A string $$$x$$$ is lexicographically smaller than a string $$$y$$$ if and only if one of the following holds: $$$x$$$ is a prefix of $$$y$$$, but $$$x \neq y$$$;  in the first position where $$$x$$$ and $$$y$$$ differ, the string $$$x$$$ has a letter that appears earlier in the alphabet than the corresponding letter in $$$y$$$.",[]322"Polycarpus likes studying at school a lot and he is always diligent about his homework. Polycarpus has never had any problems with natural sciences as his great-great-grandfather was the great physicist Seinstein. On the other hand though, Polycarpus has never had an easy time with history.Everybody knows that the World history encompasses exactly n events: the i-th event had continued from the year ai to the year bi inclusive (ai < bi). Polycarpus easily learned the dates when each of n events started and ended (Polycarpus inherited excellent memory from his great-great-granddad). But the teacher gave him a more complicated task: Polycaprus should know when all events began and ended and he should also find out for each event whether it includes another event. Polycarpus' teacher thinks that an event j includes an event i if aj < ai and bi < bj. Your task is simpler: find the number of events that are included in some other event.",[]323"Roman planted a tree consisting of n vertices. Each vertex contains a lowercase English letter. Vertex 1 is the root of the tree, each of the n - 1 remaining vertices has a parent in the tree. Vertex is connected with its parent by an edge. The parent of vertex i is vertex pi, the parent index is always less than the index of the vertex (i.e., pi < i).The depth of the vertex is the number of nodes on the path from the root to v along the edges. In particular, the depth of the root is equal to 1.We say that vertex u is in the subtree of vertex v, if we can get from u to v, moving from the vertex to the parent. In particular, vertex v is in its subtree.Roma gives you m queries, the i-th of which consists of two numbers vi, hi. Let's consider the vertices in the subtree vi located at depth hi. Determine whether you can use the letters written at these vertices to make a string that is a palindrome. The letters that are written in the vertexes, can be rearranged in any order to make a palindrome, but all letters should be used.","['graphs', 'trees']"324"You have a string $$$s$$$ — a sequence of commands for your toy robot. The robot is placed in some cell of a rectangular grid. He can perform four commands:  'W' — move one cell up;  'S' — move one cell down;  'A' — move one cell left;  'D' — move one cell right. Let $$$Grid(s)$$$ be the grid of minimum possible area such that there is a position in the grid where you can place the robot in such a way that it will not fall from the grid while running the sequence of commands $$$s$$$. For example, if $$$s = \text{DSAWWAW}$$$ then $$$Grid(s)$$$ is the $$$4 \times 3$$$ grid:  you can place the robot in the cell $$$(3, 2)$$$;  the robot performs the command 'D' and moves to $$$(3, 3)$$$;  the robot performs the command 'S' and moves to $$$(4, 3)$$$;  the robot performs the command 'A' and moves to $$$(4, 2)$$$;  the robot performs the command 'W' and moves to $$$(3, 2)$$$;  the robot performs the command 'W' and moves to $$$(2, 2)$$$;  the robot performs the command 'A' and moves to $$$(2, 1)$$$;  the robot performs the command 'W' and moves to $$$(1, 1)$$$.   You have $$$4$$$ extra letters: one 'W', one 'A', one 'S', one 'D'. You'd like to insert at most one of these letters in any position of sequence $$$s$$$ to minimize the area of $$$Grid(s)$$$.What is the minimum area of $$$Grid(s)$$$ you can achieve?","['math', 'strings']"325"There are $$$n$$$ points on the plane, the $$$i$$$-th of which is at $$$(x_i, y_i)$$$. Tokitsukaze wants to draw a strange rectangular area and pick all the points in the area.The strange area is enclosed by three lines, $$$x = l$$$, $$$y = a$$$ and $$$x = r$$$, as its left side, its bottom side and its right side respectively, where $$$l$$$, $$$r$$$ and $$$a$$$ can be any real numbers satisfying that $$$l < r$$$. The upper side of the area is boundless, which you can regard as a line parallel to the $$$x$$$-axis at infinity. The following figure shows a strange rectangular area.  A point $$$(x_i, y_i)$$$ is in the strange rectangular area if and only if $$$l < x_i < r$$$ and $$$y_i > a$$$. For example, in the above figure, $$$p_1$$$ is in the area while $$$p_2$$$ is not.Tokitsukaze wants to know how many different non-empty sets she can obtain by picking all the points in a strange rectangular area, where we think two sets are different if there exists at least one point in one set of them but not in the other.",[]326"Pushok the dog has been chasing Imp for a few hours already.  Fortunately, Imp knows that Pushok is afraid of a robot vacuum cleaner. While moving, the robot generates a string t consisting of letters 's' and 'h', that produces a lot of noise. We define noise of string t as the number of occurrences of string ""sh"" as a subsequence in it, in other words, the number of such pairs (i, j), that i < j and  and . The robot is off at the moment. Imp knows that it has a sequence of strings ti in its memory, and he can arbitrary change their order. When the robot is started, it generates the string t as a concatenation of these strings in the given order. The noise of the resulting string equals the noise of this concatenation.Help Imp to find the maximum noise he can achieve by changing the order of the strings.",[]327"There is a graph of $$$n$$$ rows and $$$10^6 + 2$$$ columns, where rows are numbered from $$$1$$$ to $$$n$$$ and columns from $$$0$$$ to $$$10^6 + 1$$$:  Let's denote the node in the row $$$i$$$ and column $$$j$$$ by $$$(i, j)$$$.Initially for each $$$i$$$ the $$$i$$$-th row has exactly one obstacle — at node $$$(i, a_i)$$$. You want to move some obstacles so that you can reach node $$$(n, 10^6+1)$$$ from node $$$(1, 0)$$$ by moving through edges of this graph (you can't pass through obstacles). Moving one obstacle to an adjacent by edge free node costs $$$u$$$ or $$$v$$$ coins, as below:  If there is an obstacle in the node $$$(i, j)$$$, you can use $$$u$$$ coins to move it to $$$(i-1, j)$$$ or $$$(i+1, j)$$$, if such node exists and if there is no obstacle in that node currently.  If there is an obstacle in the node $$$(i, j)$$$, you can use $$$v$$$ coins to move it to $$$(i, j-1)$$$ or $$$(i, j+1)$$$, if such node exists and if there is no obstacle in that node currently.  Note that you can't move obstacles outside the grid. For example, you can't move an obstacle from $$$(1,1)$$$ to $$$(0,1)$$$. Refer to the picture above for a better understanding. Now you need to calculate the minimal number of coins you need to spend to be able to reach node $$$(n, 10^6+1)$$$ from node $$$(1, 0)$$$ by moving through edges of this graph without passing through obstacles.",['math']328"In Walrusland public transport tickets are characterized by two integers: by the number of the series and by the number of the ticket in the series. Let the series number be represented by a and the ticket number — by b, then a ticket is described by the ordered pair of numbers (a, b). The walruses believe that a ticket is lucky if a * b = rev(a) * rev(b). The function rev(x) reverses a number written in the decimal system, at that the leading zeroes disappear. For example, rev(12343) = 34321, rev(1200) = 21.The Public Transport Management Committee wants to release x series, each containing y tickets, so that at least w lucky tickets were released and the total number of released tickets (x * y) were minimum. The series are numbered from 1 to x inclusive. The tickets in each series are numbered from 1 to y inclusive. The Transport Committee cannot release more than maxx series and more than maxy tickets in one series.",[]329"As a teacher, Riko Hakozaki often needs to help her students with problems from various subjects. Today, she is asked a programming task which goes as follows.You are given an undirected complete graph with $$$n$$$ nodes, where some edges are pre-assigned with a positive weight while the rest aren't. You need to assign all unassigned edges with non-negative weights so that in the resulting fully-assigned complete graph the XOR sum of all weights would be equal to $$$0$$$.Define the ugliness of a fully-assigned complete graph the weight of its minimum spanning tree, where the weight of a spanning tree equals the sum of weights of its edges. You need to assign the weights so that the ugliness of the resulting graph is as small as possible.As a reminder, an undirected complete graph with $$$n$$$ nodes contains all edges $$$(u, v)$$$ with $$$1 \le u < v \le n$$$; such a graph has $$$\frac{n(n-1)}{2}$$$ edges.She is not sure how to solve this problem, so she asks you to solve it for her.","['graphs', 'trees']"330"Inna loves digit 9 very much. That's why she asked Dima to write a small number consisting of nines. But Dima must have misunderstood her and he wrote a very large number a, consisting of digits from 1 to 9.Inna wants to slightly alter the number Dima wrote so that in the end the number contained as many digits nine as possible. In one move, Inna can choose two adjacent digits in a number which sum equals 9 and replace them by a single digit 9.For instance, Inna can alter number 14545181 like this: 14545181 → 1945181 → 194519 → 19919. Also, she can use this method to transform number 14545181 into number 19991. Inna will not transform it into 149591 as she can get numbers 19919 and 19991 which contain more digits nine.Dima is a programmer so he wants to find out how many distinct numbers containing as many digits nine as possible Inna can get from the written number. Help him with this challenging task.",[]331"The only difference between the two versions is that this version asks the maximal possible answer.Homer likes arrays a lot. Today he is painting an array $$$a_1, a_2, \dots, a_n$$$ with two kinds of colors, white and black. A painting assignment for $$$a_1, a_2, \dots, a_n$$$ is described by an array $$$b_1, b_2, \dots, b_n$$$ that $$$b_i$$$ indicates the color of $$$a_i$$$ ($$$0$$$ for white and $$$1$$$ for black).According to a painting assignment $$$b_1, b_2, \dots, b_n$$$, the array $$$a$$$ is split into two new arrays $$$a^{(0)}$$$ and $$$a^{(1)}$$$, where $$$a^{(0)}$$$ is the sub-sequence of all white elements in $$$a$$$ and $$$a^{(1)}$$$ is the sub-sequence of all black elements in $$$a$$$. For example, if $$$a = [1,2,3,4,5,6]$$$ and $$$b = [0,1,0,1,0,0]$$$, then $$$a^{(0)} = [1,3,5,6]$$$ and $$$a^{(1)} = [2,4]$$$.The number of segments in an array $$$c_1, c_2, \dots, c_k$$$, denoted $$$\mathit{seg}(c)$$$, is the number of elements if we merge all adjacent elements with the same value in $$$c$$$. For example, the number of segments in $$$[1,1,2,2,3,3,3,2]$$$ is $$$4$$$, because the array will become $$$[1,2,3,2]$$$ after merging adjacent elements with the same value. Especially, the number of segments in an empty array is $$$0$$$.Homer wants to find a painting assignment $$$b$$$, according to which the number of segments in both $$$a^{(0)}$$$ and $$$a^{(1)}$$$, i.e. $$$\mathit{seg}(a^{(0)})+\mathit{seg}(a^{(1)})$$$, is as large as possible. Find this number.",[]332"Fox Ciel is playing a card game with her friend Jiro.Jiro has n cards, each one has two attributes: position (Attack or Defense) and strength. Fox Ciel has m cards, each one has these two attributes too. It's known that position of all Ciel's cards is Attack.Now is Ciel's battle phase, Ciel can do the following operation many times:  Choose one of her cards X. This card mustn't be chosen before.  If Jiro has no alive cards at that moment, he gets the damage equal to (X's strength). Otherwise, Ciel needs to choose one Jiro's alive card Y, then:   If Y's position is Attack, then (X's strength)  ≥  (Y's strength) must hold. After this attack, card Y dies, and Jiro gets the damage equal to (X's strength) - (Y's strength).  If Y's position is Defense, then (X's strength)  >  (Y's strength) must hold. After this attack, card Y dies, but Jiro gets no damage.  Ciel can end her battle phase at any moment (so, she can use not all her cards). Help the Fox to calculate the maximal sum of damage Jiro can get.",[]333"On the way to school, Karen became fixated on the puzzle game on her phone!  The game is played as follows. In each level, you have a grid with n rows and m columns. Each cell originally contains the number 0.One move consists of choosing one row or column, and adding 1 to all of the cells in that row or column.To win the level, after all the moves, the number in the cell at the i-th row and j-th column should be equal to gi, j.Karen is stuck on one level, and wants to know a way to beat this level using the minimum number of moves. Please, help her with this task!",[]334"In one school with Vasya there is a student Kostya. Kostya does not like physics, he likes different online games. Every day, having come home, Kostya throws his bag in the farthest corner and sits down at his beloved computer. Kostya even eats glued to the game. A few days ago Kostya bought a new RPG game ""HaresButtle"", which differs from all other games in this genre. It has a huge number of artifacts. As we know, artifacts are divided into basic and composite ones. Only the basic artifacts are available on sale. More powerful composite artifacts are collected from some number of basic artifacts.After the composing composite artifact, all the components disappear.Kostya is the head of the alliance, so he has to remember, what artifacts has not only himself, but also his allies. You must identify by sequence of artifacts purchased by Kostya and his allies, how many and which artifacts has been collected by each of them. It is believed that initially no one has any artifacts. ",[]335"You have a directed acyclic graph G, consisting of n vertexes, numbered from 0 to n - 1. The graph contains n edges numbered from 0 to n - 1. An edge with number i connects vertexes i and (i + 1) mod n, and it can be directed in either direction (from i to (i + 1) mod n, or vise versa).Operation x mod y means taking the remainder after dividing number x by number y.Let's call two vertexes u and v in graph G comparable if the graph contains a path either from u to v or from v to u. We'll assume that an antichain is a set of vertexes of graph G, where any two distinct vertexes are not comparable. The size of an antichain is the number of vertexes in the corresponding set. An antichain is maximum if the graph doesn't have antichains of a larger size.Your task is to find the size of the maximum antichain in graph G.",[]336"In order to do some research, $$$n^2$$$ labs are built on different heights of a mountain. Let's enumerate them with integers from $$$1$$$ to $$$n^2$$$, such that the lab with the number $$$1$$$ is at the lowest place, the lab with the number $$$2$$$ is at the second-lowest place, $$$\ldots$$$, the lab with the number $$$n^2$$$ is at the highest place.To transport water between the labs, pipes are built between every pair of labs. A pipe can transport at most one unit of water at a time from the lab with the number $$$u$$$ to the lab with the number $$$v$$$ if $$$u > v$$$.Now the labs need to be divided into $$$n$$$ groups, each group should contain exactly $$$n$$$ labs. The labs from different groups can transport water to each other. The sum of units of water that can be sent from a group $$$A$$$ to a group $$$B$$$ is equal to the number of pairs of labs ($$$u, v$$$) such that the lab with the number $$$u$$$ is from the group $$$A$$$, the lab with the number $$$v$$$ is from the group $$$B$$$ and $$$u > v$$$. Let's denote this value as $$$f(A,B)$$$ (i.e. $$$f(A,B)$$$ is the sum of units of water that can be sent from a group $$$A$$$ to a group $$$B$$$).For example, if $$$n=3$$$ and there are $$$3$$$ groups $$$X$$$, $$$Y$$$ and $$$Z$$$: $$$X = \{1, 5, 6\}, Y = \{2, 4, 9\}$$$ and $$$Z = \{3, 7, 8\}$$$. In this case, the values of $$$f$$$ are equal to:  $$$f(X,Y)=4$$$ because of $$$5 \rightarrow 2$$$, $$$5 \rightarrow 4$$$, $$$6 \rightarrow 2$$$, $$$6 \rightarrow 4$$$,  $$$f(X,Z)=2$$$ because of $$$5 \rightarrow 3$$$, $$$6 \rightarrow 3$$$,  $$$f(Y,X)=5$$$ because of $$$2 \rightarrow 1$$$, $$$4 \rightarrow 1$$$, $$$9 \rightarrow 1$$$, $$$9 \rightarrow 5$$$, $$$9 \rightarrow 6$$$,  $$$f(Y,Z)=4$$$ because of $$$4 \rightarrow 3$$$, $$$9 \rightarrow 3$$$, $$$9 \rightarrow 7$$$, $$$9 \rightarrow 8$$$,  $$$f(Z,X)=7$$$ because of $$$3 \rightarrow 1$$$, $$$7 \rightarrow 1$$$, $$$7 \rightarrow 5$$$, $$$7 \rightarrow 6$$$, $$$8 \rightarrow 1$$$, $$$8 \rightarrow 5$$$, $$$8 \rightarrow 6$$$,  $$$f(Z,Y)=5$$$ because of $$$3 \rightarrow 2$$$, $$$7 \rightarrow 2$$$, $$$7 \rightarrow 4$$$, $$$8 \rightarrow 2$$$, $$$8 \rightarrow 4$$$. Please, divide labs into $$$n$$$ groups with size $$$n$$$, such that the value $$$\min f(A,B)$$$ over all possible pairs of groups $$$A$$$ and $$$B$$$ ($$$A \neq B$$$) is maximal.In other words, divide labs into $$$n$$$ groups with size $$$n$$$, such that minimum number of the sum of units of water that can be transported from a group $$$A$$$ to a group $$$B$$$ for every pair of different groups $$$A$$$ and $$$B$$$ ($$$A \neq B$$$) as big as possible.Note, that the example above doesn't demonstrate an optimal division, but it demonstrates how to calculate the values $$$f$$$ for some division.If there are many optimal divisions, you can find any.",[]337"Inna and Dima bought a table of size n × m in the shop. Each cell of the table contains a single letter: ""D"", ""I"", ""M"", ""A"".Inna loves Dima, so she wants to go through his name as many times as possible as she moves through the table. For that, Inna acts as follows:  initially, Inna chooses some cell of the table where letter ""D"" is written;  then Inna can move to some side-adjacent table cell that contains letter ""I""; then from this cell she can go to one of the side-adjacent table cells that contains the written letter ""M""; then she can go to a side-adjacent cell that contains letter ""A"". Then Inna assumes that she has gone through her sweetheart's name;  Inna's next move can be going to one of the side-adjacent table cells that contains letter ""D"" and then walk on through name DIMA in the similar manner. Inna never skips a letter. So, from the letter ""D"" she always goes to the letter ""I"", from the letter ""I"" she always goes the to letter ""M"", from the letter ""M"" she always goes to the letter ""A"", and from the letter ""A"" she always goes to the letter ""D"". Depending on the choice of the initial table cell, Inna can go through name DIMA either an infinite number of times or some positive finite number of times or she can't go through his name once. Help Inna find out what maximum number of times she can go through name DIMA.",['graphs']338"In Absurdistan, there are n towns (numbered 1 through n) and m bidirectional railways. There is also an absurdly simple road network — for each pair of different towns x and y, there is a bidirectional road between towns x and y if and only if there is no railway between them. Travelling to a different town using one railway or one road always takes exactly one hour.A train and a bus leave town 1 at the same time. They both have the same destination, town n, and don't make any stops on the way (but they can wait in town n). The train can move only along railways and the bus can move only along roads.You've been asked to plan out routes for the vehicles; each route can use any road/railway multiple times. One of the most important aspects to consider is safety — in order to avoid accidents at railway crossings, the train and the bus must not arrive at the same town (except town n) simultaneously.Under these constraints, what is the minimum number of hours needed for both vehicles to reach town n (the maximum of arrival times of the bus and the train)? Note, that bus and train are not required to arrive to the town n at the same moment of time, but are allowed to do so.",['graphs']339"Reading books is one of Sasha's passions. Once while he was reading one book, he became acquainted with an unusual character. The character told about himself like that: ""Many are my names in many countries. Mithrandir among the Elves, Tharkûn to the Dwarves, Olórin I was in my youth in the West that is forgotten, in the South Incánus, in the North Gandalf; to the East I go not.""And at that moment Sasha thought, how would that character be called in the East? In the East all names are palindromes. A string is a palindrome if it reads the same backward as forward. For example, such strings as ""kazak"", ""oo"" and ""r"" are palindromes, but strings ""abb"" and ""ij"" are not. Sasha believed that the hero would be named after one of the gods of the East. As long as there couldn't be two equal names, so in the East people did the following: they wrote the original name as a string on a piece of paper, then cut the paper minimum number of times $$$k$$$, so they got $$$k+1$$$ pieces of paper with substrings of the initial string, and then unite those pieces together to get a new string. Pieces couldn't be turned over, they could be shuffled.In this way, it's possible to achive a string abcdefg from the string f|de|abc|g using $$$3$$$ cuts (by swapping papers with substrings f and abc). The string cbadefg can't be received using the same cuts.More formally, Sasha wants for the given palindrome $$$s$$$ find such minimum $$$k$$$, that you can cut this string into $$$k + 1$$$ parts, and then unite them in such a way that the final string will be a palindrome and it won't be equal to the initial string $$$s$$$. It there is no answer, then print ""Impossible"" (without quotes).",['strings']340"The main city magazine offers its readers an opportunity to publish their ads. The format of the ad should be like this:There are space-separated non-empty words of lowercase and uppercase Latin letters.There are hyphen characters '-' in some words, their positions set word wrapping points. Word can include more than one hyphen. It is guaranteed that there are no adjacent spaces and no adjacent hyphens. No hyphen is adjacent to space. There are no spaces and no hyphens before the first word and after the last word. When the word is wrapped, the part of the word before hyphen and the hyphen itself stay on current line and the next part of the word is put on the next line. You can also put line break between two words, in that case the space stays on current line. Check notes for better understanding.The ad can occupy no more that k lines and should have minimal width. The width of the ad is the maximal length of string (letters, spaces and hyphens are counted) in it.You should write a program that will find minimal width of the ad.",[]341"Vova is playing a computer game. There are in total $$$n$$$ turns in the game and Vova really wants to play all of them. The initial charge of his laptop battery (i.e. the charge before the start of the game) is $$$k$$$.During each turn Vova can choose what to do:   If the current charge of his laptop battery is strictly greater than $$$a$$$, Vova can just play, and then the charge of his laptop battery will decrease by $$$a$$$;  if the current charge of his laptop battery is strictly greater than $$$b$$$ ($$$b<a$$$), Vova can play and charge his laptop, and then the charge of his laptop battery will decrease by $$$b$$$;  if the current charge of his laptop battery is less than or equal to $$$a$$$ and $$$b$$$ at the same time then Vova cannot do anything and loses the game. Regardless of Vova's turns the charge of the laptop battery is always decreases.Vova wants to complete the game (Vova can complete the game if after each of $$$n$$$ turns the charge of the laptop battery is strictly greater than $$$0$$$). Vova has to play exactly $$$n$$$ turns. Among all possible ways to complete the game, Vova wants to choose the one where the number of turns when he just plays (first type turn) is the maximum possible. It is possible that Vova cannot complete the game at all.Your task is to find out the maximum possible number of turns Vova can just play (make the first type turn) or report that Vova cannot complete the game.You have to answer $$$q$$$ independent queries.",['math']342You are given n segments on the coordinate axis Ox and the number k. The point is satisfied if it belongs to at least k segments. Find the smallest (by the number of segments) set of segments on the coordinate axis Ox which contains all satisfied points and no others.,[]343"Santa has $$$n$$$ candies and he wants to gift them to $$$k$$$ kids. He wants to divide as many candies as possible between all $$$k$$$ kids. Santa can't divide one candy into parts but he is allowed to not use some candies at all.Suppose the kid who recieves the minimum number of candies has $$$a$$$ candies and the kid who recieves the maximum number of candies has $$$b$$$ candies. Then Santa will be satisfied, if the both conditions are met at the same time:  $$$b - a \le 1$$$ (it means $$$b = a$$$ or $$$b = a + 1$$$);  the number of kids who has $$$a+1$$$ candies (note that $$$a+1$$$ not necessarily equals $$$b$$$) does not exceed $$$\lfloor\frac{k}{2}\rfloor$$$ (less than or equal to $$$\lfloor\frac{k}{2}\rfloor$$$). $$$\lfloor\frac{k}{2}\rfloor$$$ is $$$k$$$ divided by $$$2$$$ and rounded down to the nearest integer. For example, if $$$k=5$$$ then $$$\lfloor\frac{k}{2}\rfloor=\lfloor\frac{5}{2}\rfloor=2$$$.Your task is to find the maximum number of candies Santa can give to kids so that he will be satisfied.You have to answer $$$t$$$ independent test cases.",['math']344"This is the easy version of the problem. The only difference between the easy and the hard versions are removal queries, they are present only in the hard version.""Interplanetary Software, Inc."" together with ""Robots of Cydonia, Ltd."" has developed and released robot cats. These electronic pets can meow, catch mice and entertain the owner in various ways.The developers from ""Interplanetary Software, Inc."" have recently decided to release a software update for these robots. After the update, the cats must solve the problems about bracket sequences. One of the problems is described below.  First, we need to learn a bit of bracket sequence theory. Consider the strings that contain characters ""("", "")"" and ""."". Call a string regular bracket sequence (RBS), if it can be transformed to an empty string by one or more operations of removing either single ""."" characters, or a continuous substring ""()"". For instance, the string ""(()(.))"" is an RBS, as it can be transformed to an empty string with the following sequence of removals: ""(()(.))"" $$$\rightarrow$$$ ""(()())"" $$$\rightarrow$$$ ""(())"" $$$\rightarrow$$$ ""()"" $$$\rightarrow$$$ """". We got an empty string, so the initial string was an RBS. At the same time, the string "")("" is not an RBS, as it is not possible to apply such removal operations to it.An RBS is simple if this RBS is not empty, doesn't start with ""."", and doesn't end with ""."".Denote the substring of the string $$$s$$$ as its sequential subsegment. In particular, $$$s[l\dots r] = s_ls_{l+1}\dots s_r$$$, where $$$s_i$$$ is the $$$i$$$-th character of the string $$$s$$$.Now, move on to the problem statement itself. You are given a string $$$s$$$, initially consisting of characters ""("" and "")"". You need to answer the queries of the following kind.Given two indices, $$$l$$$ and $$$r$$$ ($$$1 \le l < r \le n$$$), and it's guaranteed that the substring $$$s[l\dots r]$$$ is a simple RBS. You need to find the number of substrings in $$$s[l\dots r]$$$ such that they are simple RBS. In other words, find the number of index pairs $$$i$$$, $$$j$$$ such that $$$l \le i < j \le r$$$ and $$$s[i\dots j]$$$ is a simple RBS.You are an employee in ""Interplanetary Software, Inc."" and you were given the task to teach the cats to solve the problem above, after the update.Note that the ""."" character cannot appear in the string in this version of the problem. It is only needed for the hard version.","['graphs', 'trees']"345"  Some time ago Slastyona the Sweetmaid decided to open her own bakery! She bought required ingredients and a wonder-oven which can bake several types of cakes, and opened the bakery.Soon the expenses started to overcome the income, so Slastyona decided to study the sweets market. She learned it's profitable to pack cakes in boxes, and that the more distinct cake types a box contains (let's denote this number as the value of the box), the higher price it has.She needs to change the production technology! The problem is that the oven chooses the cake types on its own and Slastyona can't affect it. However, she knows the types and order of n cakes the oven is going to bake today. Slastyona has to pack exactly k boxes with cakes today, and she has to put in each box several (at least one) cakes the oven produced one right after another (in other words, she has to put in a box a continuous segment of cakes).Slastyona wants to maximize the total value of all boxes with cakes. Help her determine this maximum possible total value.",[]346"There is a rectangular grid of n rows of m initially-white cells each.Arkady performed a certain number (possibly zero) of operations on it. In the i-th operation, a non-empty subset of rows Ri and a non-empty subset of columns Ci are chosen. For each row r in Ri and each column c in Ci, the intersection of row r and column c is coloured black.There's another constraint: a row or a column can only be chosen at most once among all operations. In other words, it means that no pair of (i, j) (i < j) exists such that  or , where  denotes intersection of sets, and  denotes the empty set.You are to determine whether a valid sequence of operations exists that produces a given final grid.",[]347"Let's denote the size of the maximum matching in a graph $$$G$$$ as $$$\mathit{MM}(G)$$$.You are given a bipartite graph. The vertices of the first part are numbered from $$$1$$$ to $$$n$$$, the vertices of the second part are numbered from $$$n+1$$$ to $$$2n$$$. Each vertex's degree is $$$2$$$.For a tuple of four integers $$$(l, r, L, R)$$$, where $$$1 \le l \le r \le n$$$ and $$$n+1 \le L \le R \le 2n$$$, let's define $$$G'(l, r, L, R)$$$ as the graph which consists of all vertices of the given graph that are included in the segment $$$[l, r]$$$ or in the segment $$$[L, R]$$$, and all edges of the given graph such that each of their endpoints belongs to one of these segments. In other words, to obtain $$$G'(l, r, L, R)$$$ from the original graph, you have to remove all vertices $$$i$$$ such that $$$i \notin [l, r]$$$ and $$$i \notin [L, R]$$$, and all edges incident to these vertices.Calculate the sum of $$$\mathit{MM}(G(l, r, L, R))$$$ over all tuples of integers $$$(l, r, L, R)$$$ having $$$1 \le l \le r \le n$$$ and $$$n+1 \le L \le R \le 2n$$$.",['math']348"To learn as soon as possible the latest news about their favourite fundamentally new operating system, BolgenOS community from Nizhni Tagil decided to develop a scheme. According to this scheme a community member, who is the first to learn the news, calls some other member, the latter, in his turn, calls some third member, and so on; i.e. a person with index i got a person with index fi, to whom he has to call, if he learns the news. With time BolgenOS community members understood that their scheme doesn't work sometimes — there were cases when some members didn't learn the news at all. Now they want to supplement the scheme: they add into the scheme some instructions of type (xi, yi), which mean that person xi has to call person yi as well. What is the minimum amount of instructions that they need to add so, that at the end everyone learns the news, no matter who is the first to learn it?","['graphs', 'trees']"349"Daniel is organizing a football tournament. He has come up with the following tournament format:   In the first several (possibly zero) stages, while the number of teams is even, they split in pairs and play one game for each pair. At each stage the loser of each pair is eliminated (there are no draws). Such stages are held while the number of teams is even.  Eventually there will be an odd number of teams remaining. If there is one team remaining, it will be declared the winner, and the tournament ends. Otherwise each of the remaining teams will play with each other remaining team once in round robin tournament (if there are x teams, there will be  games), and the tournament ends. For example, if there were 20 teams initially, they would begin by playing 10 games. So, 10 teams would be eliminated, and the remaining 10 would play 5 games. Then the remaining 5 teams would play 10 games in a round robin tournament. In total there would be 10+5+10=25 games.Daniel has already booked the stadium for n games. Help him to determine how many teams he should invite so that the tournament needs exactly n games. You should print all possible numbers of teams that will yield exactly n games in ascending order, or -1 if there are no such numbers.",['math']350"3R2 - Standby for ActionOur dear Cafe's owner, JOE Miller, will soon take part in a new game TV-show ""1 vs. $$$n$$$""!The game goes in rounds, where in each round the host asks JOE and his opponents a common question. All participants failing to answer are eliminated. The show ends when only JOE remains (we assume that JOE never answers a question wrong!).For each question JOE answers, if there are $$$s$$$ ($$$s > 0$$$) opponents remaining and $$$t$$$ ($$$0 \le t \le s$$$) of them make a mistake on it, JOE receives $$$\displaystyle\frac{t}{s}$$$ dollars, and consequently there will be $$$s - t$$$ opponents left for the next question.JOE wonders what is the maximum possible reward he can receive in the best possible scenario. Yet he has little time before show starts, so can you help him answering it instead?",['math']351"You are given a complete undirected graph with n vertices. A number ai is assigned to each vertex, and the weight of an edge between vertices i and j is equal to ai xor aj.Calculate the weight of the minimum spanning tree in this graph.",[]352"Valera takes part in the Berland Marathon. The marathon race starts at the stadium that can be represented on the plane as a square whose lower left corner is located at point with coordinates (0, 0) and the length of the side equals a meters. The sides of the square are parallel to coordinate axes.As the length of the marathon race is very long, Valera needs to have extra drink during the race. The coach gives Valera a bottle of drink each d meters of the path. We know that Valera starts at the point with coordinates (0, 0) and runs counter-clockwise. That is, when Valera covers a meters, he reaches the point with coordinates (a, 0). We also know that the length of the marathon race equals nd + 0.5 meters. Help Valera's coach determine where he should be located to help Valera. Specifically, determine the coordinates of Valera's positions when he covers d, 2·d, ..., n·d meters.",['math']353"Polycarpus participates in a competition for hacking into a new secure messenger. He's almost won.Having carefully studied the interaction protocol, Polycarpus came to the conclusion that the secret key can be obtained if he properly cuts the public key of the application into two parts. The public key is a long integer which may consist of even a million digits!Polycarpus needs to find such a way to cut the public key into two nonempty parts, that the first (left) part is divisible by a as a separate number, and the second (right) part is divisible by b as a separate number. Both parts should be positive integers that have no leading zeros. Polycarpus knows values a and b.Help Polycarpus and find any suitable method to cut the public key.","['math', 'strings', 'number theory']"354"A string $$$a=a_1a_2\dots a_n$$$ is called even if it consists of a concatenation (joining) of strings of length $$$2$$$ consisting of the same characters. In other words, a string $$$a$$$ is even if two conditions are satisfied at the same time:  its length $$$n$$$ is even;  for all odd $$$i$$$ ($$$1 \le i \le n - 1$$$), $$$a_i = a_{i+1}$$$ is satisfied. For example, the following strings are even: """" (empty string), ""tt"", ""aabb"", ""oooo"", and ""ttrrrroouuuuuuuukk"". The following strings are not even: ""aaa"", ""abab"" and ""abba"".Given a string $$$s$$$ consisting of lowercase Latin letters. Find the minimum number of characters to remove from the string $$$s$$$ to make it even. The deleted characters do not have to be consecutive.",['strings']355"New Year is coming, and Jaehyun decided to read many books during 2015, unlike this year. He has n books numbered by integers from 1 to n. The weight of the i-th (1 ≤ i ≤ n) book is wi.As Jaehyun's house is not large enough to have a bookshelf, he keeps the n books by stacking them vertically. When he wants to read a certain book x, he follows the steps described below.  He lifts all the books above book x.  He pushes book x out of the stack.  He puts down the lifted books without changing their order.  After reading book x, he puts book x on the top of the stack.  He decided to read books for m days. In the j-th (1 ≤ j ≤ m) day, he will read the book that is numbered with integer bj (1 ≤ bj ≤ n). To read the book, he has to use the process described in the paragraph above. It is possible that he decides to re-read the same book several times.After making this plan, he realized that the total weight of books he should lift during m days would be too heavy. So, he decided to change the order of the stacked books before the New Year comes, and minimize the total weight. You may assume that books can be stacked in any possible order. Note that book that he is going to read on certain step isn't considered as lifted on that step. Can you help him?",['math']356"Nadeko's birthday is approaching! As she decorated the room for the party, a long garland of Dianthus-shaped paper pieces was placed on a prominent part of the wall. Brother Koyomi will like it!Still unsatisfied with the garland, Nadeko decided to polish it again. The garland has n pieces numbered from 1 to n from left to right, and the i-th piece has a colour si, denoted by a lowercase English letter. Nadeko will repaint at most m of the pieces to give each of them an arbitrary new colour (still denoted by a lowercase English letter). After this work, she finds out all subsegments of the garland containing pieces of only colour c — Brother Koyomi's favourite one, and takes the length of the longest among them to be the Koyomity of the garland.For instance, let's say the garland is represented by ""kooomo"", and Brother Koyomi's favourite colour is ""o"". Among all subsegments containing pieces of ""o"" only, ""ooo"" is the longest, with a length of 3. Thus the Koyomity of this garland equals 3.But problem arises as Nadeko is unsure about Brother Koyomi's favourite colour, and has swaying ideas on the amount of work to do. She has q plans on this, each of which can be expressed as a pair of an integer mi and a lowercase letter ci, meanings of which are explained above. You are to find out the maximum Koyomity achievable after repainting the garland according to each plan.",['strings']357"Tomorrow is a difficult day for Polycarp: he has to attend $$$a$$$ lectures and $$$b$$$ practical classes at the university! Since Polycarp is a diligent student, he is going to attend all of them.While preparing for the university, Polycarp wonders whether he can take enough writing implements to write all of the lectures and draw everything he has to during all of the practical classes. Polycarp writes lectures using a pen (he can't use a pencil to write lectures!); he can write down $$$c$$$ lectures using one pen, and after that it runs out of ink. During practical classes Polycarp draws blueprints with a pencil (he can't use a pen to draw blueprints!); one pencil is enough to draw all blueprints during $$$d$$$ practical classes, after which it is unusable.Polycarp's pencilcase can hold no more than $$$k$$$ writing implements, so if Polycarp wants to take $$$x$$$ pens and $$$y$$$ pencils, they will fit in the pencilcase if and only if $$$x + y \le k$$$.Now Polycarp wants to know how many pens and pencils should he take. Help him to determine it, or tell that his pencilcase doesn't have enough room for all the implements he needs tomorrow!Note that you don't have to minimize the number of writing implements (though their total number must not exceed $$$k$$$).",['math']358"Long ago, when Petya was a schoolboy, he was very much interested in the Petr# language grammar. During one lesson Petya got interested in the following question: how many different continuous substrings starting with the sbegin and ending with the send (it is possible sbegin = send), the given string t has. Substrings are different if and only if their contents aren't equal, their positions of occurence don't matter. Petya wasn't quite good at math, that's why he couldn't count this number. Help him!",['strings']359"Given an array $$$a$$$ of $$$n$$$ integers and an integer $$$k$$$ ($$$2 \le k \le n$$$), where each element of the array is denoted by $$$a_i$$$ ($$$0 \le i < n$$$). Perform the operation $$$z$$$ given below on $$$a$$$ and print the value of $$$z(a,k)$$$ modulo $$$10^{9}+7$$$.function z(array a, integer k):    if length(a) < k:        return 0    else:        b = empty array        ans = 0        for i = 0 .. (length(a) - k):            temp = a[i]            for j = i .. (i + k - 1):                temp = max(temp, a[j])            append temp to the end of b            ans = ans + temp        return ans + z(b, k)",['math']360You are given an undirected connected weighted graph consisting of $$$n$$$ vertices and $$$m$$$ edges. Let's denote the length of the shortest path from vertex $$$1$$$ to vertex $$$i$$$ as $$$d_i$$$. You have to erase some edges of the graph so that at most $$$k$$$ edges remain. Let's call a vertex $$$i$$$ good if there still exists a path from $$$1$$$ to $$$i$$$ with length $$$d_i$$$ after erasing the edges.Your goal is to erase the edges in such a way that the number of good vertices is maximized.,['graphs']361"During the lesson small girl Alyona works with one famous spreadsheet computer program and learns how to edit tables.Now she has a table filled with integers. The table consists of n rows and m columns. By ai, j we will denote the integer located at the i-th row and the j-th column. We say that the table is sorted in non-decreasing order in the column j if ai, j ≤ ai + 1, j for all i from 1 to n - 1.Teacher gave Alyona k tasks. For each of the tasks two integers l and r are given and Alyona has to answer the following question: if one keeps the rows from l to r inclusive and deletes all others, will the table be sorted in non-decreasing order in at least one column? Formally, does there exist such j that ai, j ≤ ai + 1, j for all i from l to r - 1 inclusive.Alyona is too small to deal with this task and asks you to help!",[]362"You are given several queries. In the i-th query you are given a single positive integer ni. You are to represent ni as a sum of maximum possible number of composite summands and print this maximum number, or print -1, if there are no such splittings.An integer greater than 1 is composite, if it is not prime, i.e. if it has positive divisors not equal to 1 and the integer itself.","['math', 'number theory']"363"You are given a permutation $$$p_1, p_2, \dots, p_n$$$. A permutation of length $$$n$$$ is a sequence such that each integer between $$$1$$$ and $$$n$$$ occurs exactly once in the sequence.Find the number of pairs of indices $$$(l, r)$$$ ($$$1 \le l \le r \le n$$$) such that the value of the median of $$$p_l, p_{l+1}, \dots, p_r$$$ is exactly the given number $$$m$$$.The median of a sequence is the value of the element which is in the middle of the sequence after sorting it in non-decreasing order. If the length of the sequence is even, the left of two middle elements is used.For example, if $$$a=[4, 2, 7, 5]$$$ then its median is $$$4$$$ since after sorting the sequence, it will look like $$$[2, 4, 5, 7]$$$ and the left of two middle elements is equal to $$$4$$$. The median of $$$[7, 1, 2, 9, 6]$$$ equals $$$6$$$ since after sorting, the value $$$6$$$ will be in the middle of the sequence.Write a program to find the number of pairs of indices $$$(l, r)$$$ ($$$1 \le l \le r \le n$$$) such that the value of the median of $$$p_l, p_{l+1}, \dots, p_r$$$ is exactly the given number $$$m$$$.",[]364"Seryozha has a very changeable character. This time he refused to leave the room to Dima and his girlfriend (her hame is Inna, by the way). However, the two lovebirds can always find a way to communicate. Today they are writing text messages to each other.Dima and Inna are using a secret code in their text messages. When Dima wants to send Inna some sentence, he writes out all words, inserting a heart before each word and after the last word. A heart is a sequence of two characters: the ""less"" characters (<) and the digit three (3). After applying the code, a test message looks like that: <3word1<3word2<3 ... wordn<3.Encoding doesn't end here. Then Dima inserts a random number of small English characters, digits, signs ""more"" and ""less"" into any places of the message.Inna knows Dima perfectly well, so she knows what phrase Dima is going to send her beforehand. Inna has just got a text message. Help her find out if Dima encoded the message correctly. In other words, find out if a text message could have been received by encoding in the manner that is described above.",['strings']365"Little Vasya loves orange juice very much. That's why any food and drink in his kitchen necessarily contains orange juice. There are n drinks in his fridge, the volume fraction of orange juice in the i-th drink equals pi percent.One day Vasya decided to make himself an orange cocktail. He took equal proportions of each of the n drinks and mixed them. Then he wondered, how much orange juice the cocktail has.Find the volume fraction of orange juice in the final drink.",['math']366"Nikolay has only recently started in competitive programming, but already qualified to the finals of one prestigious olympiad. There going to be $$$n$$$ participants, one of whom is Nikolay. Like any good olympiad, it consists of two rounds. Tired of the traditional rules, in which the participant who solved the largest number of problems wins, the organizers came up with different rules.Suppose in the first round participant A took $$$x$$$-th place and in the second round — $$$y$$$-th place. Then the total score of the participant A is sum $$$x + y$$$. The overall place of the participant A is the number of participants (including A) having their total score less than or equal to the total score of A. Note, that some participants may end up having a common overall place. It is also important to note, that in both the first and the second round there were no two participants tying at a common place. In other words, for every $$$i$$$ from $$$1$$$ to $$$n$$$ exactly one participant took $$$i$$$-th place in first round and exactly one participant took $$$i$$$-th place in second round.Right after the end of the Olympiad, Nikolay was informed that he got $$$x$$$-th place in first round and $$$y$$$-th place in the second round. Nikolay doesn't know the results of other participants, yet he wonders what is the minimum and maximum place he can take, if we consider the most favorable and unfavorable outcome for him. Please help Nikolay to find the answer to this question.",['math']367"Polycarpus develops an interesting theory about the interrelation of arithmetic progressions with just everything in the world. His current idea is that the population of the capital of Berland changes over time like an arithmetic progression. Well, or like multiple arithmetic progressions.Polycarpus believes that if he writes out the population of the capital for several consecutive years in the sequence a1, a2, ..., an, then it is convenient to consider the array as several arithmetic progressions, written one after the other. For example, sequence (8, 6, 4, 2, 1, 4, 7, 10, 2) can be considered as a sequence of three arithmetic progressions (8, 6, 4, 2), (1, 4, 7, 10) and (2), which are written one after another.Unfortunately, Polycarpus may not have all the data for the n consecutive years (a census of the population doesn't occur every year, after all). For this reason, some values of ai ​​may be unknown. Such values are represented by number -1.For a given sequence a = (a1, a2, ..., an), which consists of positive integers and values ​​-1, find the minimum number of arithmetic progressions Polycarpus needs to get a. To get a, the progressions need to be written down one after the other. Values ​​-1 may correspond to an arbitrary positive integer and the values ai > 0 must be equal to the corresponding elements of sought consecutive record of the progressions.Let us remind you that a finite sequence c is called an arithmetic progression if the difference ci + 1 - ci of any two consecutive elements in it is constant. By definition, any sequence of length 1 is an arithmetic progression.",['math']368"A widely known among some people Belarusian sport programmer Lesha decided to make some money to buy a one square meter larger flat. To do this, he wants to make and carry out a Super Rated Match (SRM) on the site Torcoder.com. But there's a problem — a severe torcoder coordinator Ivan does not accept any Lesha's problem, calling each of them an offensive word ""duped"" (that is, duplicated). And one day they nearely quarrelled over yet another problem Ivan wouldn't accept.You are invited to act as a fair judge and determine whether the problem is indeed brand new, or Ivan is right and the problem bears some resemblance to those used in the previous SRMs.You are given the descriptions of Lesha's problem and each of Torcoder.com archive problems. The description of each problem is a sequence of words. Besides, it is guaranteed that Lesha's problem has no repeated words, while the description of an archive problem may contain any number of repeated words.The ""similarity"" between Lesha's problem and some archive problem can be found as follows. Among all permutations of words in Lesha's problem we choose the one that occurs in the archive problem as a subsequence. If there are multiple such permutations, we choose the one with the smallest number of inversions. Then the ""similarity"" of a problem can be written as , where n is the number of words in Lesha's problem and x is the number of inversions in the chosen permutation. Note that the ""similarity"" p is always a positive integer.The problem is called brand new if there is not a single problem in Ivan's archive which contains a permutation of words from Lesha's problem as a subsequence.Help the boys and determine whether the proposed problem is new, or specify the problem from the archive which resembles Lesha's problem the most, otherwise.",[]369"Lunar New Year is approaching, and Bob decides to take a wander in a nearby park.The park can be represented as a connected graph with $$$n$$$ nodes and $$$m$$$ bidirectional edges. Initially Bob is at the node $$$1$$$ and he records $$$1$$$ on his notebook. He can wander from one node to another through those bidirectional edges. Whenever he visits a node not recorded on his notebook, he records it. After he visits all nodes at least once, he stops wandering, thus finally a permutation of nodes $$$a_1, a_2, \ldots, a_n$$$ is recorded.Wandering is a boring thing, but solving problems is fascinating. Bob wants to know the lexicographically smallest sequence of nodes he can record while wandering. Bob thinks this problem is trivial, and he wants you to solve it.A sequence $$$x$$$ is lexicographically smaller than a sequence $$$y$$$ if and only if one of the following holds:   $$$x$$$ is a prefix of $$$y$$$, but $$$x \ne y$$$ (this is impossible in this problem as all considered sequences have the same length);  in the first position where $$$x$$$ and $$$y$$$ differ, the sequence $$$x$$$ has a smaller element than the corresponding element in $$$y$$$. ",['graphs']370"This is an interactive problem!Ehab has a hidden permutation $$$p$$$ of length $$$n$$$ consisting of the elements from $$$0$$$ to $$$n-1$$$. You, for some reason, want to figure out the permutation. To do that, you can give Ehab $$$2$$$ different indices $$$i$$$ and $$$j$$$, and he'll reply with $$$(p_i|p_j)$$$ where $$$|$$$ is the bitwise-or operation.Ehab has just enough free time to answer $$$4269$$$ questions, and while he's OK with answering that many questions, he's too lazy to play your silly games, so he'll fix the permutation beforehand and will not change it depending on your queries. Can you guess the permutation?",['probabilities']371"A long time ago, in a galaxy far far away two giant IT-corporations Pineapple and Gogol continue their fierce competition. Crucial moment is just around the corner: Gogol is ready to release it's new tablet Lastus 3000.This new device is equipped with specially designed artificial intelligence (AI). Employees of Pineapple did their best to postpone the release of Lastus 3000 as long as possible. Finally, they found out, that the name of the new artificial intelligence is similar to the name of the phone, that Pineapple released 200 years ago. As all rights on its name belong to Pineapple, they stand on changing the name of Gogol's artificial intelligence.Pineapple insists, that the name of their phone occurs in the name of AI as a substring. Because the name of technology was already printed on all devices, the Gogol's director decided to replace some characters in AI name with ""#"". As this operation is pretty expensive, you should find the minimum number of characters to replace with ""#"", such that the name of AI doesn't contain the name of the phone as a substring.Substring is a continuous subsequence of a string.",['strings']372"There are n people taking dancing lessons. Every person is characterized by his/her dancing skill ai. At the beginning of the lesson they line up from left to right. While there is at least one couple of a boy and a girl in the line, the following process is repeated: the boy and girl who stand next to each other, having the minimal difference in dancing skills start to dance. If there are several such couples, the one first from the left starts to dance. After a couple leaves to dance, the line closes again, i.e. as a result the line is always continuous. The difference in dancing skills is understood as the absolute value of difference of ai variable. Your task is to find out what pairs and in what order will start dancing.",[]373"Someone gave Alyona an array containing n positive integers a1, a2, ..., an. In one operation, Alyona can choose any element of the array and decrease it, i.e. replace with any positive integer that is smaller than the current one. Alyona can repeat this operation as many times as she wants. In particular, she may not apply any operation to the array at all.Formally, after applying some operations Alyona will get an array of n positive integers b1, b2, ..., bn such that 1 ≤ bi ≤ ai for every 1 ≤ i ≤ n. Your task is to determine the maximum possible value of mex of this array.Mex of an array in this problem is the minimum positive integer that doesn't appear in this array. For example, mex of the array containing 1, 3 and 4 is equal to 2, while mex of the array containing 2, 3 and 2 is equal to 1.",[]374"You have $$$n$$$ chains, the $$$i$$$-th chain consists of $$$c_i$$$ vertices. Vertices in each chain are numbered independently from $$$1$$$ to $$$c_i$$$ along the chain. In other words, the $$$i$$$-th chain is the undirected graph with $$$c_i$$$ vertices and $$$(c_i - 1)$$$ edges connecting the $$$j$$$-th and the $$$(j + 1)$$$-th vertices for each $$$1 \le j < c_i$$$.Now you decided to unite chains in one graph in the following way:   the first chain is skipped;  the $$$1$$$-st vertex of the $$$i$$$-th chain is connected by an edge with the $$$a_i$$$-th vertex of the $$$(i - 1)$$$-th chain;  the last ($$$c_i$$$-th) vertex of the $$$i$$$-th chain is connected by an edge with the $$$b_i$$$-th vertex of the $$$(i - 1)$$$-th chain.   Picture of the first test case. Dotted lines are the edges added during uniting process Calculate the length of the longest simple cycle in the resulting graph.A simple cycle is a chain where the first and last vertices are connected as well. If you travel along the simple cycle, each vertex of this cycle will be visited exactly once.",['graphs']375"You have integer $$$n$$$. Calculate how many ways are there to fully cover belt-like area of $$$4n-2$$$ triangles with diamond shapes. Diamond shape consists of two triangles. You can move, rotate or flip the shape, but you cannot scale it. $$$2$$$ coverings are different if some $$$2$$$ triangles are covered by the same diamond shape in one of them and by different diamond shapes in the other one.Please look at pictures below for better understanding.  On the left you can see the diamond shape you will use, and on the right you can see the area you want to fill. These are the figures of the area you want to fill for $$$n = 1, 2, 3, 4$$$. You have to answer $$$t$$$ independent test cases.",['math']376"You are given a table consisting of n rows and m columns.Numbers in each row form a permutation of integers from 1 to m.You are allowed to pick two elements in one row and swap them, but no more than once for each row. Also, no more than once you are allowed to pick two columns and swap them. Thus, you are allowed to perform from 0 to n + 1 actions in total. Operations can be performed in any order.You have to check whether it's possible to obtain the identity permutation 1, 2, ..., m in each row. In other words, check if one can perform some of the operation following the given rules and make each row sorted in increasing order.",['math']377"You are given n strings s1, s2, ..., sn consisting of characters 0 and 1. m operations are performed, on each of them you concatenate two existing strings into a new one. On the i-th operation the concatenation saisbi is saved into a new string sn + i (the operations are numbered starting from 1). After each operation you need to find the maximum positive integer k such that all possible strings consisting of 0 and 1 of length k (there are 2k such strings) are substrings of the new string. If there is no such k, print 0.",['strings']378"In the game Lizard Era: Beginning the protagonist will travel with three companions: Lynn, Meliana and Worrigan. Overall the game has n mandatory quests. To perform each of them, you need to take exactly two companions.The attitude of each of the companions to the hero is an integer. Initially, the attitude of each of them to the hero of neutral and equal to 0. As the hero completes quests, he makes actions that change the attitude of the companions, whom he took to perform this task, in positive or negative direction.Tell us what companions the hero needs to choose to make their attitude equal after completing all the quests. If this can be done in several ways, choose the one in which the value of resulting attitude is greatest possible.",[]379"Vasya decided to pass a very large integer n to Kate. First, he wrote that number as a string, then he appended to the right integer k — the number of digits in n. Magically, all the numbers were shuffled in arbitrary order while this note was passed to Kate. The only thing that Vasya remembers, is a non-empty substring of n (a substring of n is a sequence of consecutive digits of the number n).Vasya knows that there may be more than one way to restore the number n. Your task is to find the smallest possible initial integer n. Note that decimal representation of number n contained no leading zeroes, except the case the integer n was equal to zero itself (in this case a single digit 0 was used).",['strings']380"This is an interactive problem.Ayush devised yet another scheme to set the password of his lock. The lock has $$$n$$$ slots where each slot can hold any non-negative integer. The password $$$P$$$ is a sequence of $$$n$$$ integers, $$$i$$$-th element of which goes into the $$$i$$$-th slot of the lock.To set the password, Ayush comes up with an array $$$A$$$ of $$$n$$$ integers each in the range $$$[0, 2^{63}-1]$$$. He then sets the $$$i$$$-th element of $$$P$$$ as the bitwise OR of all integers in the array except $$$A_i$$$.You need to guess the password. To make a query, you can choose a non-empty subset of indices of the array and ask the bitwise OR all elements of the array with index in this subset. You can ask no more than 13 queries.",['math']381"ZS the Coder and Chris the Baboon has arrived at Udayland! They walked in the park where n trees grow. They decided to be naughty and color the trees in the park. The trees are numbered with integers from 1 to n from left to right.Initially, tree i has color ci. ZS the Coder and Chris the Baboon recognizes only m different colors, so 0 ≤ ci ≤ m, where ci = 0 means that tree i is uncolored.ZS the Coder and Chris the Baboon decides to color only the uncolored trees, i.e. the trees with ci = 0. They can color each of them them in any of the m colors from 1 to m. Coloring the i-th tree with color j requires exactly pi, j litres of paint.The two friends define the beauty of a coloring of the trees as the minimum number of contiguous groups (each group contains some subsegment of trees) you can split all the n trees into so that each group contains trees of the same color. For example, if the colors of the trees from left to right are 2, 1, 1, 1, 3, 2, 2, 3, 1, 3, the beauty of the coloring is 7, since we can partition the trees into 7 contiguous groups of the same color : {2}, {1, 1, 1}, {3}, {2, 2}, {3}, {1}, {3}. ZS the Coder and Chris the Baboon wants to color all uncolored trees so that the beauty of the coloring is exactly k. They need your help to determine the minimum amount of paint (in litres) needed to finish the job.Please note that the friends can't color the trees that are already colored.",[]382"The Cereal Guy's friend Serial Guy likes to watch soap operas. An episode is about to start, and he hasn't washed his plate yet. But he decided to at least put in under the tap to be filled with water. The plate can be represented by a parallelepiped k × n × m, that is, it has k layers (the first layer is the upper one), each of which is a rectangle n × m with empty squares ('.') and obstacles ('#'). The water can only be present in the empty squares. The tap is positioned above the square (x, y) of the first layer, it is guaranteed that this square is empty. Every minute a cubical unit of water falls into the plate. Find out in how many minutes the Serial Guy should unglue himself from the soap opera and turn the water off for it not to overfill the plate. That is, you should find the moment of time when the plate is absolutely full and is going to be overfilled in the next moment.Note: the water fills all the area within reach (see sample 4). Water flows in each of the 6 directions, through faces of 1 × 1 × 1 cubes.",[]383You are given a string S of length n with each character being one of the first m lowercase English letters. Calculate how many different strings T of length n composed from the first m lowercase English letters exist such that the length of LCS (longest common subsequence) between S and T is n - 1.Recall that LCS of two strings S and T is the longest string C such that C both in S and T as a subsequence.,[]384"After the most stunning success with the fifth-graders, Madoka has been trusted with teaching the sixth-graders.There's $$$n$$$ single-place desks in her classroom. At the very beginning Madoka decided that the student number $$$b_i$$$ ($$$1 \le b_i \le n$$$) will sit at the desk number $$$i$$$. Also there's an infinite line of students with numbers $$$n + 1, n + 2, n + 3, \ldots$$$ waiting at the door with the hope of being able to learn something from the Madoka herself. Pay attention that each student has his unique number.After each lesson, the following happens in sequence.   The student sitting at the desk $$$i$$$ moves to the desk $$$p_i$$$. All students move simultaneously.  If there is more than one student at a desk, the student with the lowest number keeps the place, and the others are removed from the class forever.  For all empty desks in ascending order, the student from the lowest number from the outside line occupies the desk. Note that in the end there is exactly one student at each desk again. It is guaranteed that the numbers $$$p$$$ are such that at least one student is removed after each lesson. Check out the explanation to the first example for a better understanding.After several (possibly, zero) lessons the desk $$$i$$$ is occupied by student $$$a_i$$$. Given the values $$$a_1, a_2, \ldots, a_n$$$ and $$$p_1, p_2, \ldots, p_n$$$, find the lexicographically smallest suitable initial seating permutation $$$b_1, b_2, \ldots, b_n$$$.The permutation is an array of $$$n$$$ different integers from $$$1$$$ up to $$$n$$$ in any order. For example, $$$[2,3,1,5,4]$$$ is a permutation, but $$$[1,2,2]$$$ is not ($$$2$$$ occurs twice). $$$[1,3,4]$$$ is not a permutation either ($$$n=3$$$ but there's $$$4$$$ in the array).For two different permutations $$$a$$$ and $$$b$$$ of the same length, $$$a$$$ is lexicographically less than $$$b$$$ if in the first position where $$$a$$$ and $$$b$$$ differ, the permutation $$$a$$$ has a smaller element than the corresponding element in $$$b$$$.",[]385"There are n cities situated along the main road of Berland. Cities are represented by their coordinates — integer numbers a1, a2, ..., an. All coordinates are pairwise distinct.It is possible to get from one city to another only by bus. But all buses and roads are very old, so the Minister of Transport decided to build a new bus route. The Minister doesn't want to spend large amounts of money — he wants to choose two cities in such a way that the distance between them is minimal possible. The distance between two cities is equal to the absolute value of the difference between their coordinates.It is possible that there are multiple pairs of cities with minimal possible distance, so the Minister wants to know the quantity of such pairs. Your task is to write a program that will calculate the minimal possible distance between two pairs of cities and the quantity of pairs which have this distance.",[]386"Vasya has an array of integers of length n.Vasya performs the following operations on the array: on each step he finds the longest segment of consecutive equal integers (the leftmost, if there are several such segments) and removes it. For example, if Vasya's array is [13, 13, 7, 7, 7, 2, 2, 2], then after one operation it becomes [13, 13, 2, 2, 2].Compute the number of operations Vasya should make until the array becomes empty, i.e. Vasya removes all elements from it.",[]387"Arnie the Worm has finished eating an apple house yet again and decided to move. He made up his mind on the plan, the way the rooms are located and how they are joined by corridors. He numbered all the rooms from 1 to n. All the corridors are bidirectional.Arnie wants the new house to look just like the previous one. That is, it should have exactly n rooms and, if a corridor from room i to room j existed in the old house, it should be built in the new one. We know that during the house constructing process Arnie starts to eat an apple starting from some room and only stops when he eats his way through all the corridors and returns to the starting room. It is also known that Arnie eats without stopping. That is, until Arnie finishes constructing the house, he is busy every moment of his time gnawing a new corridor. Arnie doesn't move along the already built corridors.However, gnawing out corridors in one and the same order any time you change a house is a very difficult activity. That's why Arnie, knowing the order in which the corridors were located in the previous house, wants to gnaw corridors in another order. It is represented as a list of rooms in the order in which they should be visited. The new list should be lexicographically smallest, but it also should be strictly lexicographically greater than the previous one. Help the worm. ",['graphs']388"You are given a line of $$$n$$$ colored squares in a row, numbered from $$$1$$$ to $$$n$$$ from left to right. The $$$i$$$-th square initially has the color $$$c_i$$$.Let's say, that two squares $$$i$$$ and $$$j$$$ belong to the same connected component if $$$c_i = c_j$$$, and $$$c_i = c_k$$$ for all $$$k$$$ satisfying $$$i < k < j$$$. In other words, all squares on the segment from $$$i$$$ to $$$j$$$ should have the same color.For example, the line $$$[3, 3, 3]$$$ has $$$1$$$ connected component, while the line $$$[5, 2, 4, 4]$$$ has $$$3$$$ connected components.The game ""flood fill"" is played on the given line as follows:   At the start of the game you pick any starting square (this is not counted as a turn).  Then, in each game turn, change the color of the connected component containing the starting square to any other color. Find the minimum number of turns needed for the entire line to be changed into a single color.",[]389"Note that the memory limit in this problem is lower than in others.You have a vertical strip with $$$n$$$ cells, numbered consecutively from $$$1$$$ to $$$n$$$ from top to bottom.You also have a token that is initially placed in cell $$$n$$$. You will move the token up until it arrives at cell $$$1$$$.Let the token be in cell $$$x > 1$$$ at some moment. One shift of the token can have either of the following kinds:   Subtraction: you choose an integer $$$y$$$ between $$$1$$$ and $$$x-1$$$, inclusive, and move the token from cell $$$x$$$ to cell $$$x - y$$$.  Floored division: you choose an integer $$$z$$$ between $$$2$$$ and $$$x$$$, inclusive, and move the token from cell $$$x$$$ to cell $$$\lfloor \frac{x}{z} \rfloor$$$ ($$$x$$$ divided by $$$z$$$ rounded down). Find the number of ways to move the token from cell $$$n$$$ to cell $$$1$$$ using one or more shifts, and print it modulo $$$m$$$. Note that if there are several ways to move the token from one cell to another in one shift, all these ways are considered distinct (check example explanation for a better understanding).","['math', 'number theory']"390"Peter wrote on the board a strictly increasing sequence of positive integers a1, a2, ..., an. Then Vasil replaced some digits in the numbers of this sequence by question marks. Thus, each question mark corresponds to exactly one lost digit.Restore the the original sequence knowing digits remaining on the board.",[]391"Police headquarter is monitoring signal on different frequency levels. They have got two suspiciously encoded strings s1 and s2 from two different frequencies as signals. They are suspecting that these two strings are from two different criminals and they are planning to do some evil task.Now they are trying to find a common substring of minimum length between these two strings. The substring must occur only once in the first string, and also it must occur only once in the second string.Given two strings s1 and s2 consist of lowercase Latin letters, find the smallest (by length) common substring p of both s1 and s2, where p is a unique substring in s1 and also in s2. See notes for formal definition of substring and uniqueness.",['strings']392"A tree is an undirected connected graph without cycles.Let's consider a rooted undirected tree with n vertices, numbered 1 through n. There are many ways to represent such a tree. One way is to create an array with n integers p1, p2, ..., pn, where pi denotes a parent of vertex i (here, for convenience a root is considered its own parent).    For this rooted tree the array p is [2, 3, 3, 2]. Given a sequence p1, p2, ..., pn, one is able to restore a tree:  There must be exactly one index r that pr = r. A vertex r is a root of the tree.  For all other n - 1 vertices i, there is an edge between vertex i and vertex pi. A sequence p1, p2, ..., pn is called valid if the described procedure generates some (any) rooted tree. For example, for n = 3 sequences (1,2,2), (2,3,1) and (2,1,3) are not valid.You are given a sequence a1, a2, ..., an, not necessarily valid. Your task is to change the minimum number of elements, in order to get a valid sequence. Print the minimum number of changes and an example of a valid sequence after that number of changes. If there are many valid sequences achievable in the minimum number of changes, print any of them.","['graphs', 'trees']"393"Ivan plays an old action game called Heretic. He's stuck on one of the final levels of this game, so he needs some help with killing the monsters.The main part of the level is a large corridor (so large and narrow that it can be represented as an infinite coordinate line). The corridor is divided into two parts; let's assume that the point $$$x = 0$$$ is where these parts meet.The right part of the corridor is filled with $$$n$$$ monsters — for each monster, its initial coordinate $$$x_i$$$ is given (and since all monsters are in the right part, every $$$x_i$$$ is positive).The left part of the corridor is filled with crusher traps. If some monster enters the left part of the corridor or the origin (so, its current coordinate becomes less than or equal to $$$0$$$), it gets instantly killed by a trap.The main weapon Ivan uses to kill the monsters is the Phoenix Rod. It can launch a missile that explodes upon impact, obliterating every monster caught in the explosion and throwing all other monsters away from the epicenter. Formally, suppose that Ivan launches a missile so that it explodes in the point $$$c$$$. Then every monster is either killed by explosion or pushed away. Let some monster's current coordinate be $$$y$$$, then:  if $$$c = y$$$, then the monster is killed;  if $$$y < c$$$, then the monster is pushed $$$r$$$ units to the left, so its current coordinate becomes $$$y - r$$$;  if $$$y > c$$$, then the monster is pushed $$$r$$$ units to the right, so its current coordinate becomes $$$y + r$$$. Ivan is going to kill the monsters as follows: choose some integer point $$$d$$$ and launch a missile into that point, then wait until it explodes and all the monsters which are pushed to the left part of the corridor are killed by crusher traps, then, if at least one monster is still alive, choose another integer point (probably the one that was already used) and launch a missile there, and so on.What is the minimum number of missiles Ivan has to launch in order to kill all of the monsters? You may assume that every time Ivan fires the Phoenix Rod, he chooses the impact point optimally.You have to answer $$$q$$$ independent queries.",[]394"Michael and Joe are playing a game. The game is played on a grid with $$$n$$$ rows and $$$m$$$ columns, filled with distinct integers. We denote the square on the $$$i$$$-th ($$$1\le i\le n$$$) row and $$$j$$$-th ($$$1\le j\le m$$$) column by $$$(i, j)$$$ and the number there by $$$a_{ij}$$$.Michael starts by saying two numbers $$$h$$$ ($$$1\le h \le n$$$) and $$$w$$$ ($$$1\le w \le m$$$). Then Joe picks any $$$h\times w$$$ subrectangle of the board (without Michael seeing).Formally, an $$$h\times w$$$ subrectangle starts at some square $$$(a,b)$$$ where $$$1 \le a \le n-h+1$$$ and $$$1 \le b \le m-w+1$$$. It contains all squares $$$(i,j)$$$ for $$$a \le i \le a+h-1$$$ and $$$b \le j \le b+w-1$$$.    Possible move by Joe if Michael says $$$3\times 2$$$ (with maximum of $$$15$$$). Finally, Michael has to guess the maximum number in the subrectangle. He wins if he gets it right.Because Michael doesn't like big numbers, he wants the area of the chosen subrectangle (that is, $$$h \cdot w$$$), to be as small as possible, while still ensuring that he wins, not depending on Joe's choice. Help Michael out by finding this minimum possible area. It can be shown that Michael can always choose $$$h, w$$$ for which he can ensure that he wins.",['games']395"One drew a closed polyline on a plane, that consisted only of vertical and horizontal segments (parallel to the coordinate axes). The segments alternated between horizontal and vertical ones (a horizontal segment was always followed by a vertical one, and vice versa). The polyline did not contain strict self-intersections, which means that in case any two segments shared a common point, that point was an endpoint for both of them (please consult the examples in the notes section).Unfortunately, the polyline was erased, and you only know the lengths of the horizonal and vertical segments. Please construct any polyline matching the description with such segments, or determine that it does not exist.",['geometry']396"You are given two strings $$$s$$$ and $$$t$$$, both consisting of lowercase English letters. You are going to type the string $$$s$$$ character by character, from the first character to the last one.When typing a character, instead of pressing the button corresponding to it, you can press the ""Backspace"" button. It deletes the last character you have typed among those that aren't deleted yet (or does nothing if there are no characters in the current string). For example, if $$$s$$$ is ""abcbd"" and you press Backspace instead of typing the first and the fourth characters, you will get the string ""bd"" (the first press of Backspace deletes no character, and the second press deletes the character 'c'). Another example, if $$$s$$$ is ""abcaa"" and you press Backspace instead of the last two letters, then the resulting text is ""a"".Your task is to determine whether you can obtain the string $$$t$$$, if you type the string $$$s$$$ and press ""Backspace"" instead of typing several (maybe zero) characters of $$$s$$$.",['strings']397"A bracket sequence is called regular if it is possible to obtain correct arithmetic expression by inserting characters «+» and «1» into this sequence. For example, sequences «(())()», «()» and «(()(()))» are regular, while «)(», «(()» and «(()))(» are not.One day Johnny got bracket sequence. He decided to remove some of the brackets from it in order to obtain a regular bracket sequence. What is the maximum length of a regular bracket sequence which can be obtained?",[]398"Vasya often uses public transport. The transport in the city is of two types: trolleys and buses. The city has n buses and m trolleys, the buses are numbered by integers from 1 to n, the trolleys are numbered by integers from 1 to m.Public transport is not free. There are 4 types of tickets:   A ticket for one ride on some bus or trolley. It costs c1 burles;  A ticket for an unlimited number of rides on some bus or on some trolley. It costs c2 burles;  A ticket for an unlimited number of rides on all buses or all trolleys. It costs c3 burles;  A ticket for an unlimited number of rides on all buses and trolleys. It costs c4 burles. Vasya knows for sure the number of rides he is going to make and the transport he is going to use. He asked you for help to find the minimum sum of burles he will have to spend on the tickets.",[]399"You are given a rooted tree of $$$2^n - 1$$$ vertices. Every vertex of this tree has either $$$0$$$ children, or $$$2$$$ children. All leaves of this tree have the same distance from the root, and for every non-leaf vertex, one of its children is the left one, and the other child is the right one. Formally, you are given a perfect binary tree.The vertices of the tree are numbered in the following order:  the root has index $$$1$$$;  if a vertex has index $$$x$$$, then its left child has index $$$2x$$$, and its right child has index $$$2x+1$$$. Every vertex of the tree has a letter written on it, either A or B. Let's define the character on the vertex $$$x$$$ as $$$s_x$$$.Let the preorder string of some vertex $$$x$$$ be defined in the following way:  if the vertex $$$x$$$ is a leaf, then the preorder string of $$$x$$$ be consisting of only one character $$$s_x$$$;  otherwise, the preorder string of $$$x$$$ is $$$s_x + f(l_x) + f(r_x)$$$, where $$$+$$$ operator defines concatenation of strings, $$$f(l_x)$$$ is the preorder string of the left child of $$$x$$$, and $$$f(r_x)$$$ is the preorder string of the right child of $$$x$$$. The preorder string of the tree is the preorder string of its root.Now, for the problem itself...You have to calculate the number of different strings that can be obtained as the preorder string of the given tree, if you are allowed to perform the following operation any number of times before constructing the preorder string of the tree:  choose any non-leaf vertex $$$x$$$, and swap its children (so, the left child becomes the right one, and vice versa). ",['trees']400"A PIN code is a string that consists of exactly $$$4$$$ digits. Examples of possible PIN codes: 7013, 0000 and 0990. Please note that the PIN code can begin with any digit, even with 0.Polycarp has $$$n$$$ ($$$2 \le n \le 10$$$) bank cards, the PIN code of the $$$i$$$-th card is $$$p_i$$$.Polycarp has recently read a recommendation that it is better to set different PIN codes on different cards. Thus he wants to change the minimal number of digits in the PIN codes of his cards so that all $$$n$$$ codes would become different.Formally, in one step, Polycarp picks $$$i$$$-th card ($$$1 \le i \le n$$$), then in its PIN code $$$p_i$$$ selects one position (from $$$1$$$ to $$$4$$$), and changes the digit in this position to any other. He needs to change the minimum number of digits so that all PIN codes become different.Polycarp quickly solved this problem. Can you solve it?",[]401"You are given two arrays $$$a$$$ and $$$b$$$, both of length $$$n$$$.Let's define a function $$$f(l, r) = \sum\limits_{l \le i \le r} a_i \cdot b_i$$$.Your task is to reorder the elements (choose an arbitrary order of elements) of the array $$$b$$$ to minimize the value of $$$\sum\limits_{1 \le l \le r \le n} f(l, r)$$$. Since the answer can be very large, you have to print it modulo $$$998244353$$$. Note that you should minimize the answer but not its remainder.",['math']402"Formula 1 officials decided to introduce new competition. Cars are replaced by space ships and number of points awarded can differ per race.Given the current ranking in the competition and points distribution for the next race, your task is to calculate the best possible ranking for a given astronaut after the next race. It's guaranteed that given astronaut will have unique number of points before the race.",[]403"You are given one integer number $$$n$$$. Find three distinct integers $$$a, b, c$$$ such that $$$2 \le a, b, c$$$ and $$$a \cdot b \cdot c = n$$$ or say that it is impossible to do it.If there are several answers, you can print any.You have to answer $$$t$$$ independent test cases.","['math', 'number theory']"404"Limak is a little polar bear. He likes nice strings — strings of length n, consisting of lowercase English letters only.The distance between two letters is defined as the difference between their positions in the alphabet. For example, , and .Also, the distance between two nice strings is defined as the sum of distances of corresponding letters. For example, , and .Limak gives you a nice string s and an integer k. He challenges you to find any nice string s' that . Find any s' satisfying the given conditions, or print ""-1"" if it's impossible to do so.As input/output can reach huge size it is recommended to use fast input/output methods: for example, prefer to use gets/scanf/printf instead of getline/cin/cout in C++, prefer to use BufferedReader/PrintWriter instead of Scanner/System.out in Java.",['strings']405"Karafs is some kind of vegetable in shape of an 1 × h rectangle. Tavaspolis people love Karafs and they use Karafs in almost any kind of food. Tavas, himself, is crazy about Karafs.  Each Karafs has a positive integer height. Tavas has an infinite 1-based sequence of Karafses. The height of the i-th Karafs is si = A + (i - 1) × B.For a given m, let's define an m-bite operation as decreasing the height of at most m distinct not eaten Karafses by 1. Karafs is considered as eaten when its height becomes zero.Now SaDDas asks you n queries. In each query he gives you numbers l, t and m and you should find the largest number r such that l ≤ r and sequence sl, sl + 1, ..., sr can be eaten by performing m-bite no more than t times or print -1 if there is no such number r.",['math']406"The weight of a sequence is defined as the number of unordered pairs of indexes $$$(i,j)$$$ (here $$$i \lt j$$$) with same value ($$$a_{i} = a_{j}$$$). For example, the weight of sequence $$$a = [1, 1, 2, 2, 1]$$$ is $$$4$$$. The set of unordered pairs of indexes with same value are $$$(1, 2)$$$, $$$(1, 5)$$$, $$$(2, 5)$$$, and $$$(3, 4)$$$.You are given a sequence $$$a$$$ of $$$n$$$ integers. Print the sum of the weight of all subsegments of $$$a$$$. A sequence $$$b$$$ is a subsegment of a sequence $$$a$$$ if $$$b$$$ can be obtained from $$$a$$$ by deletion of several (possibly, zero or all) elements from the beginning and several (possibly, zero or all) elements from the end.",['math']407"Initially Ildar has an empty array. He performs $$$n$$$ steps. On each step he takes a subset of integers already added to the array and appends the mex of this subset to the array. The mex of an multiset of integers is the smallest non-negative integer not presented in the multiset. For example, the mex of the multiset $$$[0, 2, 3]$$$ is $$$1$$$, while the mex of the multiset $$$[1, 2, 1]$$$ is $$$0$$$.More formally, on the step $$$m$$$, when Ildar already has an array $$$a_1, a_2, \ldots, a_{m-1}$$$, he chooses some subset of indices $$$1 \leq i_1 < i_2 < \ldots < i_k < m$$$ (possibly, empty), where $$$0 \leq k < m$$$, and appends the $$$mex(a_{i_1}, a_{i_2}, \ldots a_{i_k})$$$ to the end of the array.After performing all the steps Ildar thinks that he might have made a mistake somewhere. He asks you to determine for a given array $$$a_1, a_2, \ldots, a_n$$$ the minimum step $$$t$$$ such that he has definitely made a mistake on at least one of the steps $$$1, 2, \ldots, t$$$, or determine that he could have obtained this array without mistakes.",[]408"Ujan decided to make a new wooden roof for the house. He has $$$n$$$ rectangular planks numbered from $$$1$$$ to $$$n$$$. The $$$i$$$-th plank has size $$$a_i \times 1$$$ (that is, the width is $$$1$$$ and the height is $$$a_i$$$).Now, Ujan wants to make a square roof. He will first choose some of the planks and place them side by side in some order. Then he will glue together all of these planks by their vertical sides. Finally, he will cut out a square from the resulting shape in such a way that the sides of the square are horizontal and vertical.For example, if Ujan had planks with lengths $$$4$$$, $$$3$$$, $$$1$$$, $$$4$$$ and $$$5$$$, he could choose planks with lengths $$$4$$$, $$$3$$$ and $$$5$$$. Then he can cut out a $$$3 \times 3$$$ square, which is the maximum possible. Note that this is not the only way he can obtain a $$$3 \times 3$$$ square.  What is the maximum side length of the square Ujan can get?",[]409"You are given a permutation of length $$$n$$$. Recall that the permutation is an array consisting of $$$n$$$ distinct integers from $$$1$$$ to $$$n$$$ in arbitrary order. For example, $$$[2, 3, 1, 5, 4]$$$ is a permutation, but $$$[1, 2, 2]$$$ is not a permutation ($$$2$$$ appears twice in the array) and $$$[1, 3, 4]$$$ is also not a permutation ($$$n=3$$$ but there is $$$4$$$ in the array).You can perform at most $$$n-1$$$ operations with the given permutation (it is possible that you don't perform any operations at all). The $$$i$$$-th operation allows you to swap elements of the given permutation on positions $$$i$$$ and $$$i+1$$$. Each operation can be performed at most once. The operations can be performed in arbitrary order.Your task is to find the lexicographically minimum possible permutation obtained by performing some of the given operations in some order.You can see the definition of the lexicographical order in the notes section.You have to answer $$$q$$$ independent test cases.For example, let's consider the permutation $$$[5, 4, 1, 3, 2]$$$. The minimum possible permutation we can obtain is $$$[1, 5, 2, 4, 3]$$$ and we can do it in the following way:  perform the second operation (swap the second and the third elements) and obtain the permutation $$$[5, 1, 4, 3, 2]$$$;  perform the fourth operation (swap the fourth and the fifth elements) and obtain the permutation $$$[5, 1, 4, 2, 3]$$$;  perform the third operation (swap the third and the fourth elements) and obtain the permutation $$$[5, 1, 2, 4, 3]$$$.  perform the first operation (swap the first and the second elements) and obtain the permutation $$$[1, 5, 2, 4, 3]$$$; Another example is $$$[1, 2, 4, 3]$$$. The minimum possible permutation we can obtain is $$$[1, 2, 3, 4]$$$ by performing the third operation (swap the third and the fourth elements).",[]410"Duff is addicted to meat! Malek wants to keep her happy for n days. In order to be happy in i-th day, she needs to eat exactly ai kilograms of meat.  There is a big shop uptown and Malek wants to buy meat for her from there. In i-th day, they sell meat for pi dollars per kilogram. Malek knows all numbers a1, ..., an and p1, ..., pn. In each day, he can buy arbitrary amount of meat, also he can keep some meat he has for the future.Malek is a little tired from cooking meat, so he asked for your help. Help him to minimize the total money he spends to keep Duff happy for n days. ",[]411"Kuroni is the coordinator of the next Mathforces round written by the ""Proof by AC"" team. All the preparation has been done, and he is discussing with the team about the score distribution for the round.The round consists of $$$n$$$ problems, numbered from $$$1$$$ to $$$n$$$. The problems are ordered in increasing order of difficulty, no two problems have the same difficulty. A score distribution for the round can be denoted by an array $$$a_1, a_2, \dots, a_n$$$, where $$$a_i$$$ is the score of $$$i$$$-th problem. Kuroni thinks that the score distribution should satisfy the following requirements:  The score of each problem should be a positive integer not exceeding $$$10^9$$$.  A harder problem should grant a strictly higher score than an easier problem. In other words, $$$1 \leq a_1 < a_2 < \dots < a_n \leq 10^9$$$.  The balance of the score distribution, defined as the number of triples $$$(i, j, k)$$$ such that $$$1 \leq i < j < k \leq n$$$ and $$$a_i + a_j = a_k$$$, should be exactly $$$m$$$. Help the team find a score distribution that satisfies Kuroni's requirement. In case such a score distribution does not exist, output $$$-1$$$.",['math']412"You are given two strings a and b. You have to remove the minimum possible number of consecutive (standing one after another) characters from string b in such a way that it becomes a subsequence of string a. It can happen that you will not need to remove any characters at all, or maybe you will have to remove all of the characters from b and make it empty.Subsequence of string s is any such string that can be obtained by erasing zero or more characters (not necessarily consecutive) from string s.",['strings']413"Little boy Gerald studies at school which is quite far from his house. That's why he has to go there by bus every day. The way from home to school is represented by a segment of a straight line; the segment contains exactly n + 1 bus stops. All of them are numbered with integers from 0 to n in the order in which they follow from Gerald's home. The bus stop by Gerald's home has number 0 and the bus stop by the school has number n.There are m buses running between the house and the school: the i-th bus goes from stop si to ti (si < ti), visiting all the intermediate stops in the order in which they follow on the segment. Besides, Gerald's no idiot and he wouldn't get off the bus until it is still possible to ride on it closer to the school (obviously, getting off would be completely pointless). In other words, Gerald can get on the i-th bus on any stop numbered from si to ti - 1 inclusive, but he can get off the i-th bus only on the bus stop ti.Gerald can't walk between the bus stops and he also can't move in the direction from the school to the house.Gerald wants to know how many ways he has to get from home to school. Tell him this number. Two ways are considered different if Gerald crosses some segment between the stops on different buses. As the number of ways can be too much, find the remainder of a division of this number by 1000000007 (109 + 7).",[]414"Luis has a sequence of $$$n+1$$$ integers $$$a_1, a_2, \ldots, a_{n+1}$$$. For each $$$i = 1, 2, \ldots, n+1$$$ it is guaranteed that $$$0\leq a_i < n$$$, or $$$a_i=n^2$$$. He has calculated the sum of all the elements of the sequence, and called this value $$$s$$$. Luis has lost his sequence, but he remembers the values of $$$n$$$ and $$$s$$$. Can you find the number of elements in the sequence that are equal to $$$n^2$$$?We can show that the answer is unique under the given constraints.",['math']415"Mainak has a convex polygon $$$\mathcal P$$$ with $$$n$$$ vertices labelled as $$$A_1, A_2, \ldots, A_n$$$ in a counter-clockwise fashion. The coordinates of the $$$i$$$-th point $$$A_i$$$ are given by $$$(x_i, y_i)$$$, where $$$x_i$$$ and $$$y_i$$$ are both integers.Further, it is known that the interior angle at $$$A_i$$$ is either a right angle or a proper obtuse angle. Formally it is known that:   $$$90 ^ \circ \le \angle A_{i - 1}A_{i}A_{i + 1} < 180 ^ \circ$$$, $$$\forall i \in \{1, 2, \ldots, n\}$$$ where we conventionally consider $$$A_0 = A_n$$$ and $$$A_{n + 1} = A_1$$$. Mainak's friend insisted that all points $$$Q$$$ such that there exists a chord of the polygon $$$\mathcal P$$$ passing through $$$Q$$$ with length not exceeding $$$1$$$, must be coloured $$$\color{red}{\text{red}}$$$. Mainak wants you to find the area of the coloured region formed by the $$$\color{red}{\text{red}}$$$ points.Formally, determine the area of the region $$$\mathcal S = \{Q \in \mathcal{P}$$$ | $$$Q \text{ is coloured } \color{red}{\text{red}}\}$$$.Recall that a chord of a polygon is a line segment between two points lying on the boundary (i.e. vertices or points on edges) of the polygon. ","['math', 'geometry']"416"Alice likes snow a lot! Unfortunately, this year's winter is already over, and she can't expect to have any more of it. Bob has thus bought her a gift — a large snow maker. He plans to make some amount of snow every day. On day i he will make a pile of snow of volume Vi and put it in her garden.Each day, every pile will shrink a little due to melting. More precisely, when the temperature on a given day is Ti, each pile will reduce its volume by Ti. If this would reduce the volume of a pile to or below zero, it disappears forever. All snow piles are independent of each other. Note that the pile made on day i already loses part of its volume on the same day. In an extreme case, this may mean that there are no piles left at the end of a particular day.You are given the initial pile sizes and the temperature on each day. Determine the total volume of snow melted on each day. ",[]417"John has just bought a new car and is planning a journey around the country. Country has N cities, some of which are connected by bidirectional roads. There are N - 1 roads and every city is reachable from any other city. Cities are labeled from 1 to N.John first has to select from which city he will start his journey. After that, he spends one day in a city and then travels to a randomly choosen city which is directly connected to his current one and which he has not yet visited. He does this until he can't continue obeying these rules.To select the starting city, he calls his friend Jack for advice. Jack is also starting a big casino business and wants to open casinos in some of the cities (max 1 per city, maybe nowhere). Jack knows John well and he knows that if he visits a city with a casino, he will gamble exactly once before continuing his journey.He also knows that if John enters a casino in a good mood, he will leave it in a bad mood and vice versa. Since he is John's friend, he wants him to be in a good mood at the moment when he finishes his journey. John is in a good mood before starting the journey.In how many ways can Jack select a starting city for John and cities where he will build casinos such that no matter how John travels, he will be in a good mood at the end? Print answer modulo 109 + 7.",[]418"Let's denote as L(x, p) an infinite sequence of integers y such that gcd(p, y) = 1 and y > x (where gcd is the greatest common divisor of two integer numbers), sorted in ascending order. The elements of L(x, p) are 1-indexed; for example, 9, 13 and 15 are the first, the second and the third elements of L(7, 22), respectively.You have to process t queries. Each query is denoted by three integers x, p and k, and the answer to this query is k-th element of L(x, p).","['math', 'number theory']"419"There is a binary string $$$a$$$ of length $$$n$$$. In one operation, you can select any prefix of $$$a$$$ with an equal number of $$$0$$$ and $$$1$$$ symbols. Then all symbols in the prefix are inverted: each $$$0$$$ becomes $$$1$$$ and each $$$1$$$ becomes $$$0$$$.For example, suppose $$$a=0111010000$$$.   In the first operation, we can select the prefix of length $$$8$$$ since it has four $$$0$$$'s and four $$$1$$$'s: $$$[01110100]00\to [10001011]00$$$.  In the second operation, we can select the prefix of length $$$2$$$ since it has one $$$0$$$ and one $$$1$$$: $$$[10]00101100\to [01]00101100$$$.  It is illegal to select the prefix of length $$$4$$$ for the third operation, because it has three $$$0$$$'s and one $$$1$$$. Can you transform the string $$$a$$$ into the string $$$b$$$ using some finite number of operations (possibly, none)?",['math']420"You are given a weighted undirected connected graph consisting of $$$n$$$ vertices and $$$m$$$ edges. It is guaranteed that there are no self-loops or multiple edges in the given graph.Let's define the weight of the path consisting of $$$k$$$ edges with indices $$$e_1, e_2, \dots, e_k$$$ as $$$\sum\limits_{i=1}^{k}{w_{e_i}} - \max\limits_{i=1}^{k}{w_{e_i}} + \min\limits_{i=1}^{k}{w_{e_i}}$$$, where $$$w_i$$$ — weight of the $$$i$$$-th edge in the graph.Your task is to find the minimum weight of the path from the $$$1$$$-st vertex to the $$$i$$$-th vertex for each $$$i$$$ ($$$2 \le i \le n$$$).",['graphs']421"This is a harder version of the problem. In this version $$$n \le 500\,000$$$The outskirts of the capital are being actively built up in Berland. The company ""Kernel Panic"" manages the construction of a residential complex of skyscrapers in New Berlskva. All skyscrapers are built along the highway. It is known that the company has already bought $$$n$$$ plots along the highway and is preparing to build $$$n$$$ skyscrapers, one skyscraper per plot.Architects must consider several requirements when planning a skyscraper. Firstly, since the land on each plot has different properties, each skyscraper has a limit on the largest number of floors it can have. Secondly, according to the design code of the city, it is unacceptable for a skyscraper to simultaneously have higher skyscrapers both to the left and to the right of it.Formally, let's number the plots from $$$1$$$ to $$$n$$$. Then if the skyscraper on the $$$i$$$-th plot has $$$a_i$$$ floors, it must hold that $$$a_i$$$ is at most $$$m_i$$$ ($$$1 \le a_i \le m_i$$$). Also there mustn't be integers $$$j$$$ and $$$k$$$ such that $$$j < i < k$$$ and $$$a_j > a_i < a_k$$$. Plots $$$j$$$ and $$$k$$$ are not required to be adjacent to $$$i$$$.The company wants the total number of floors in the built skyscrapers to be as large as possible. Help it to choose the number of floors for each skyscraper in an optimal way, i.e. in such a way that all requirements are fulfilled, and among all such construction plans choose any plan with the maximum possible total number of floors.",[]422"You are playing a game on a $$$n \times m$$$ grid, in which the computer has selected some cell $$$(x, y)$$$ of the grid, and you have to determine which one. To do so, you will choose some $$$k$$$ and some $$$k$$$ cells $$$(x_1, y_1),\, (x_2, y_2), \ldots, (x_k, y_k)$$$, and give them to the computer. In response, you will get $$$k$$$ numbers $$$b_1,\, b_2, \ldots b_k$$$, where $$$b_i$$$ is the manhattan distance from $$$(x_i, y_i)$$$ to the hidden cell $$$(x, y)$$$ (so you know which distance corresponds to which of $$$k$$$ input cells). After receiving these $$$b_1,\, b_2, \ldots, b_k$$$, you have to be able to determine the hidden cell. What is the smallest $$$k$$$ for which is it possible to always guess the hidden cell correctly, no matter what cell computer chooses?As a reminder, the manhattan distance between cells $$$(a_1, b_1)$$$ and $$$(a_2, b_2)$$$ is equal to $$$|a_1-a_2|+|b_1-b_2|$$$.",['math']423"Alice got a new doll these days. It can even walk!Alice has built a maze for the doll and wants to test it. The maze is a grid with $$$n$$$ rows and $$$m$$$ columns. There are $$$k$$$ obstacles, the $$$i$$$-th of them is on the cell $$$(x_i, y_i)$$$, which means the cell in the intersection of the $$$x_i$$$-th row and the $$$y_i$$$-th column.However, the doll is clumsy in some ways. It can only walk straight or turn right at most once in the same cell (including the start cell). It cannot get into a cell with an obstacle or get out of the maze.More formally, there exist $$$4$$$ directions, in which the doll can look:  The doll looks in the direction along the row from the first cell to the last. While moving looking in this direction the doll will move from the cell $$$(x, y)$$$ into the cell $$$(x, y + 1)$$$;  The doll looks in the direction along the column from the first cell to the last. While moving looking in this direction the doll will move from the cell $$$(x, y)$$$ into the cell $$$(x + 1, y)$$$;  The doll looks in the direction along the row from the last cell to first. While moving looking in this direction the doll will move from the cell $$$(x, y)$$$ into the cell $$$(x, y - 1)$$$;  The doll looks in the direction along the column from the last cell to the first. While moving looking in this direction the doll will move from the cell $$$(x, y)$$$ into the cell $$$(x - 1, y)$$$. .Standing in some cell the doll can move into the cell in the direction it looks or it can turn right once. Turning right once, the doll switches it's direction by the following rules: $$$1 \to 2$$$, $$$2 \to 3$$$, $$$3 \to 4$$$, $$$4 \to 1$$$. Standing in one cell, the doll can make at most one turn right.Now Alice is controlling the doll's moves. She puts the doll in of the cell $$$(1, 1)$$$ (the upper-left cell of the maze). Initially, the doll looks to the direction $$$1$$$, so along the row from the first cell to the last. She wants to let the doll walk across all the cells without obstacles exactly once and end in any place. Can it be achieved?",[]424"This is an interactive problem.Vasya and Vitya play a game. Vasya thought of two integers $$$a$$$ and $$$b$$$ from $$$1$$$ to $$$n$$$ and Vitya tries to guess them. Each round he tells Vasya two numbers $$$x$$$ and $$$y$$$ from $$$1$$$ to $$$n$$$. If both $$$x=a$$$ and $$$y=b$$$ then Vitya wins. Else Vasya must say one of the three phrases:   $$$x$$$ is less than $$$a$$$;  $$$y$$$ is less than $$$b$$$;  $$$x$$$ is greater than $$$a$$$ or $$$y$$$ is greater than $$$b$$$. Vasya can't lie, but if multiple phrases are true, he may choose any of them. For example, if Vasya thought of numbers $$$2$$$ and $$$4$$$, then he answers with the phrase $$$3$$$ to a query $$$(3, 4)$$$, and he can answer with the phrase $$$1$$$ or phrase $$$3$$$ to a query $$$(1, 5)$$$.Help Vitya win in no more than $$$600$$$ rounds. ",[]425"Tokitsukaze is arranging a meeting. There are $$$n$$$ rows and $$$m$$$ columns of seats in the meeting hall.There are exactly $$$n \cdot m$$$ students attending the meeting, including several naughty students and several serious students. The students are numerated from $$$1$$$ to $$$n\cdot m$$$. The students will enter the meeting hall in order. When the $$$i$$$-th student enters the meeting hall, he will sit in the $$$1$$$-st column of the $$$1$$$-st row, and the students who are already seated will move back one seat. Specifically, the student sitting in the $$$j$$$-th ($$$1\leq j \leq m-1$$$) column of the $$$i$$$-th row will move to the $$$(j+1)$$$-th column of the $$$i$$$-th row, and the student sitting in $$$m$$$-th column of the $$$i$$$-th row will move to the $$$1$$$-st column of the $$$(i+1)$$$-th row.For example, there is a meeting hall with $$$2$$$ rows and $$$2$$$ columns of seats shown as below:  There will be $$$4$$$ students entering the meeting hall in order, represented as a binary string ""1100"", of which '0' represents naughty students and '1' represents serious students. The changes of seats in the meeting hall are as follows:  Denote a row or a column good if and only if there is at least one serious student in this row or column. Please predict the number of good rows and columns just after the $$$i$$$-th student enters the meeting hall, for all $$$i$$$.",['math']426"You are given a set of all integers from $$$l$$$ to $$$r$$$ inclusive, $$$l < r$$$, $$$(r - l + 1) \le 3 \cdot 10^5$$$ and $$$(r - l)$$$ is always odd.You want to split these numbers into exactly $$$\frac{r - l + 1}{2}$$$ pairs in such a way that for each pair $$$(i, j)$$$ the greatest common divisor of $$$i$$$ and $$$j$$$ is equal to $$$1$$$. Each number should appear in exactly one of the pairs.Print the resulting pairs or output that no solution exists. If there are multiple solutions, print any of them.","['math', 'number theory']"427"Pari has a friend who loves palindrome numbers. A palindrome number is a number that reads the same forward or backward. For example 12321, 100001 and 1 are palindrome numbers, while 112 and 1021 are not.Pari is trying to love them too, but only very special and gifted people can understand the beauty behind palindrome numbers. Pari loves integers with even length (i.e. the numbers with even number of digits), so she tries to see a lot of big palindrome numbers with even length (like a 2-digit 11 or 6-digit 122221), so maybe she could see something in them.Now Pari asks you to write a program that gets a huge integer n from the input and tells what is the n-th even-length positive palindrome number?",['math']428"Asterix, Obelix and their temporary buddies Suffix and Prefix has finally found the Harmony temple. However, its doors were firmly locked and even Obelix had no luck opening them.A little later they found a string s, carved on a rock below the temple's gates. Asterix supposed that that's the password that opens the temple and read the string aloud. However, nothing happened. Then Asterix supposed that a password is some substring t of the string s.Prefix supposed that the substring t is the beginning of the string s; Suffix supposed that the substring t should be the end of the string s; and Obelix supposed that t should be located somewhere inside the string s, that is, t is neither its beginning, nor its end.Asterix chose the substring t so as to please all his companions. Besides, from all acceptable variants Asterix chose the longest one (as Asterix loves long strings). When Asterix read the substring t aloud, the temple doors opened. You know the string s. Find the substring t or determine that such substring does not exist and all that's been written above is just a nice legend.",['strings']429"Dasha has $$$10^{100}$$$ coins. Recently, she found a binary string $$$s$$$ of length $$$n$$$ and some operations that allows to change this string (she can do each operation any number of times):  Replace substring 00 of $$$s$$$ by 0 and receive $$$a$$$ coins.  Replace substring 11 of $$$s$$$ by 1 and receive $$$b$$$ coins.  Remove 0 from any position in $$$s$$$ and pay $$$c$$$ coins. It turned out that while doing this operations Dasha should follow the rule:  It is forbidden to do two operations with the same parity in a row. Operations are numbered by integers $$$1$$$-$$$3$$$ in the order they are given above. Please, calculate what is the maximum profit Dasha can get by doing these operations and following this rule.",[]430"You are given two arrays of length $$$n$$$: $$$a_1, a_2, \dots, a_n$$$ and $$$b_1, b_2, \dots, b_n$$$.You can perform the following operation any number of times:   Choose integer index $$$i$$$ ($$$1 \le i \le n$$$);  Swap $$$a_i$$$ and $$$b_i$$$. What is the minimum possible sum $$$|a_1 - a_2| + |a_2 - a_3| + \dots + |a_{n-1} - a_n|$$$ $$$+$$$ $$$|b_1 - b_2| + |b_2 - b_3| + \dots + |b_{n-1} - b_n|$$$ (in other words, $$$\sum\limits_{i=1}^{n - 1}{\left(|a_i - a_{i+1}| + |b_i - b_{i+1}|\right)}$$$) you can achieve after performing several (possibly, zero) operations?",['math']431"In Aramic language words can only represent objects.Words in Aramic have special properties:   A word is a root if it does not contain the same letter more than once.  A root and all its permutations represent the same object.  The root $$$x$$$ of a word $$$y$$$ is the word that contains all letters that appear in $$$y$$$ in a way that each letter appears once. For example, the root of ""aaaa"", ""aa"", ""aaa"" is ""a"", the root of ""aabb"", ""bab"", ""baabb"", ""ab"" is ""ab"".  Any word in Aramic represents the same object as its root. You have an ancient script in Aramic. What is the number of different objects mentioned in the script?",['strings']432"Vasya had two arrays consisting of non-negative integers: a of size n and b of size m. Vasya chose a positive integer k and created an n × m matrix v using the following formula:Vasya wrote down matrix v on a piece of paper and put it in the table.A year later Vasya was cleaning his table when he found a piece of paper containing an n × m matrix w. He remembered making a matrix one day by the rules given above but he was not sure if he had found the paper with the matrix v from those days. Your task is to find out if the matrix w that you've found could have been obtained by following these rules and if it could, then for what numbers k, a1, a2, ..., an, b1, b2, ..., bm it is possible.",['math']433"Recently, Olya received a magical square with the size of $$$2^n\times 2^n$$$.It seems to her sister that one square is boring. Therefore, she asked Olya to perform exactly $$$k$$$ splitting operations.A Splitting operation is an operation during which Olya takes a square with side $$$a$$$ and cuts it into 4 equal squares with side $$$\dfrac{a}{2}$$$. If the side of the square is equal to $$$1$$$, then it is impossible to apply a splitting operation to it (see examples for better understanding).Olya is happy to fulfill her sister's request, but she also wants the condition of Olya's happiness to be satisfied after all operations.The condition of Olya's happiness will be satisfied if the following statement is fulfilled:Let the length of the side of the lower left square be equal to $$$a$$$, then the length of the side of the right upper square should also be equal to $$$a$$$. There should also be a path between them that consists only of squares with the side of length $$$a$$$. All consecutive squares on a path should have a common side.Obviously, as long as we have one square, these conditions are met. So Olya is ready to fulfill her sister's request only under the condition that she is satisfied too. Tell her: is it possible to perform exactly $$$k$$$ splitting operations in a certain order so that the condition of Olya's happiness is satisfied? If it is possible, tell also the size of the side of squares of which the path from the lower left square to the upper right one will consist.",['math']434"There are n employees working in company ""X"" (let's number them from 1 to n for convenience). Initially the employees didn't have any relationships among each other. On each of m next days one of the following events took place:  either employee y became the boss of employee x (at that, employee x didn't have a boss before);  or employee x gets a packet of documents and signs them; then he gives the packet to his boss. The boss signs the documents and gives them to his boss and so on (the last person to sign the documents sends them to the archive);  or comes a request of type ""determine whether employee x signs certain documents"". Your task is to write a program that will, given the events, answer the queries of the described type. At that, it is guaranteed that throughout the whole working time the company didn't have cyclic dependencies.","['graphs', 'trees']"435"$$$n$$$ towns are arranged in a circle sequentially. The towns are numbered from $$$1$$$ to $$$n$$$ in clockwise order. In the $$$i$$$-th town, there lives a singer with a repertoire of $$$a_i$$$ minutes for each $$$i \in [1, n]$$$.Each singer visited all $$$n$$$ towns in clockwise order, starting with the town he lives in, and gave exactly one concert in each town. In addition, in each town, the $$$i$$$-th singer got inspired and came up with a song that lasts $$$a_i$$$ minutes. The song was added to his repertoire so that he could perform it in the rest of the cities.Hence, for the $$$i$$$-th singer, the concert in the $$$i$$$-th town will last $$$a_i$$$ minutes, in the $$$(i + 1)$$$-th town the concert will last $$$2 \cdot a_i$$$ minutes, ..., in the $$$((i + k) \bmod n + 1)$$$-th town the duration of the concert will be $$$(k + 2) \cdot a_i$$$, ..., in the town $$$((i + n - 2) \bmod n + 1)$$$ — $$$n \cdot a_i$$$ minutes.You are given an array of $$$b$$$ integer numbers, where $$$b_i$$$ is the total duration of concerts in the $$$i$$$-th town. Reconstruct any correct sequence of positive integers $$$a$$$ or say that it is impossible.",['math']436"Dreamoon likes coloring cells very much.There is a row of $$$n$$$ cells. Initially, all cells are empty (don't contain any color). Cells are numbered from $$$1$$$ to $$$n$$$.You are given an integer $$$m$$$ and $$$m$$$ integers $$$l_1, l_2, \ldots, l_m$$$ ($$$1 \le l_i \le n$$$)Dreamoon will perform $$$m$$$ operations.In $$$i$$$-th operation, Dreamoon will choose a number $$$p_i$$$ from range $$$[1, n-l_i+1]$$$ (inclusive) and will paint all cells from $$$p_i$$$ to $$$p_i+l_i-1$$$ (inclusive) in $$$i$$$-th color. Note that cells may be colored more one than once, in this case, cell will have the color from the latest operation.Dreamoon hopes that after these $$$m$$$ operations, all colors will appear at least once and all cells will be colored. Please help Dreamoon to choose $$$p_i$$$ in each operation to satisfy all constraints.",[]437"You are given three integers $$$x, y$$$ and $$$n$$$. Your task is to find the maximum integer $$$k$$$ such that $$$0 \le k \le n$$$ that $$$k \bmod x = y$$$, where $$$\bmod$$$ is modulo operation. Many programming languages use percent operator % to implement it.In other words, with given $$$x, y$$$ and $$$n$$$ you need to find the maximum possible integer from $$$0$$$ to $$$n$$$ that has the remainder $$$y$$$ modulo $$$x$$$.You have to answer $$$t$$$ independent test cases. It is guaranteed that such $$$k$$$ exists for each test case.",['math']438"Dwarfs have planted a very interesting plant, which is a triangle directed ""upwards"". This plant has an amusing feature. After one year a triangle plant directed ""upwards"" divides into four triangle plants: three of them will point ""upwards"" and one will point ""downwards"". After another year, each triangle plant divides into four triangle plants: three of them will be directed in the same direction as the parent plant, and one of them will be directed in the opposite direction. Then each year the process repeats. The figure below illustrates this process.  Help the dwarfs find out how many triangle plants that point ""upwards"" will be in n years.",['math']439"Your favorite shop sells $$$n$$$ Kinder Surprise chocolate eggs. You know that exactly $$$s$$$ stickers and exactly $$$t$$$ toys are placed in $$$n$$$ eggs in total.Each Kinder Surprise can be one of three types:  it can contain a single sticker and no toy;  it can contain a single toy and no sticker;  it can contain both a single sticker and a single toy. But you don't know which type a particular Kinder Surprise has. All eggs look identical and indistinguishable from each other.What is the minimum number of Kinder Surprise Eggs you have to buy to be sure that, whichever types they are, you'll obtain at least one sticker and at least one toy?Note that you do not open the eggs in the purchasing process, that is, you just buy some number of eggs. It's guaranteed that the answer always exists.",['math']440"Alfred wants to buy a toy moose that costs c dollars. The store doesn’t give change, so he must give the store exactly c dollars, no more and no less. He has n coins. To make c dollars from his coins, he follows the following algorithm: let S be the set of coins being used. S is initially empty. Alfred repeatedly adds to S the highest-valued coin he has such that the total value of the coins in S after adding the coin doesn’t exceed c. If there is no such coin, and the value of the coins in S is still less than c, he gives up and goes home. Note that Alfred never removes a coin from S after adding it.As a programmer, you might be aware that Alfred’s algorithm can fail even when there is a set of coins with value exactly c. For example, if Alfred has one coin worth $3, one coin worth $4, and two coins worth $5, and the moose costs $12, then Alfred will add both of the $5 coins to S and then give up, since adding any other coin would cause the value of the coins in S to exceed $12. Of course, Alfred could instead combine one $3 coin, one $4 coin, and one $5 coin to reach the total.Bob tried to convince Alfred that his algorithm was flawed, but Alfred didn’t believe him. Now Bob wants to give Alfred some coins (in addition to those that Alfred already has) such that Alfred’s algorithm fails. Bob can give Alfred any number of coins of any denomination (subject to the constraint that each coin must be worth a positive integer number of dollars). There can be multiple coins of a single denomination. He would like to minimize the total value of the coins he gives Alfred. Please find this minimum value. If there is no solution, print ""Greed is good"". You can assume that the answer, if it exists, is positive. In other words, Alfred's algorithm will work if Bob doesn't give him any coins.",[]441"Kevin and Nicky Sun have invented a new game called Lieges of Legendre. In this game, two players take turns modifying the game state with Kevin moving first. Initially, the game is set up so that there are n piles of cows, with the i-th pile containing ai cows. During each player's turn, that player calls upon the power of Sunlight, and uses it to either:  Remove a single cow from a chosen non-empty pile.  Choose a pile of cows with even size 2·x (x > 0), and replace it with k piles of x cows each. The player who removes the last cow wins. Given n, k, and a sequence a1, a2, ..., an, help Kevin and Nicky find the winner, given that both sides play in optimal way.","['math', 'games']"442"Given an integer N, find two permutations:  Permutation p of numbers from 1 to N such that pi ≠ i and pi & i = 0 for all i = 1, 2, ..., N.  Permutation q of numbers from 1 to N such that qi ≠ i and qi & i ≠ 0 for all i = 1, 2, ..., N. & is the bitwise AND operation.",[]443"On a strip of land of length $$$n$$$ there are $$$k$$$ air conditioners: the $$$i$$$-th air conditioner is placed in cell $$$a_i$$$ ($$$1 \le a_i \le n$$$). Two or more air conditioners cannot be placed in the same cell (i.e. all $$$a_i$$$ are distinct).Each air conditioner is characterized by one parameter: temperature. The $$$i$$$-th air conditioner is set to the temperature $$$t_i$$$.    Example of strip of length $$$n=6$$$, where $$$k=2$$$, $$$a=[2,5]$$$ and $$$t=[14,16]$$$. For each cell $$$i$$$ ($$$1 \le i \le n$$$) find it's temperature, that can be calculated by the formula $$$$$$\min_{1 \le j \le k}(t_j + |a_j - i|),$$$$$$where $$$|a_j - i|$$$ denotes absolute value of the difference $$$a_j - i$$$.In other words, the temperature in cell $$$i$$$ is equal to the minimum among the temperatures of air conditioners, increased by the distance from it to the cell $$$i$$$.Let's look at an example. Consider that $$$n=6, k=2$$$, the first air conditioner is placed in cell $$$a_1=2$$$ and is set to the temperature $$$t_1=14$$$ and the second air conditioner is placed in cell $$$a_2=5$$$ and is set to the temperature $$$t_2=16$$$. In that case temperatures in cells are:  temperature in cell $$$1$$$ is: $$$\min(14 + |2 - 1|, 16 + |5 - 1|)=\min(14 + 1, 16 + 4)=\min(15, 20)=15$$$;  temperature in cell $$$2$$$ is: $$$\min(14 + |2 - 2|, 16 + |5 - 2|)=\min(14 + 0, 16 + 3)=\min(14, 19)=14$$$;  temperature in cell $$$3$$$ is: $$$\min(14 + |2 - 3|, 16 + |5 - 3|)=\min(14 + 1, 16 + 2)=\min(15, 18)=15$$$;  temperature in cell $$$4$$$ is: $$$\min(14 + |2 - 4|, 16 + |5 - 4|)=\min(14 + 2, 16 + 1)=\min(16, 17)=16$$$;  temperature in cell $$$5$$$ is: $$$\min(14 + |2 - 5|, 16 + |5 - 5|)=\min(14 + 3, 16 + 0)=\min(17, 16)=16$$$;  temperature in cell $$$6$$$ is: $$$\min(14 + |2 - 6|, 16 + |5 - 6|)=\min(14 + 4, 16 + 1)=\min(18, 17)=17$$$. For each cell from $$$1$$$ to $$$n$$$ find the temperature in it.",[]444"After their adventure with the magic mirror Kay and Gerda have returned home and sometimes give free ice cream to kids in the summer.At the start of the day they have x ice cream packs. Since the ice cream is free, people start standing in the queue before Kay and Gerda's house even in the night. Each person in the queue wants either to take several ice cream packs for himself and his friends or to give several ice cream packs to Kay and Gerda (carriers that bring ice cream have to stand in the same queue).If a carrier with d ice cream packs comes to the house, then Kay and Gerda take all his packs. If a child who wants to take d ice cream packs comes to the house, then Kay and Gerda will give him d packs if they have enough ice cream, otherwise the child will get no ice cream at all and will leave in distress.Kay wants to find the amount of ice cream they will have after all people will leave from the queue, and Gerda wants to find the number of distressed kids.",[]445"Berland National Library has recently been built in the capital of Berland. In addition, in the library you can take any of the collected works of Berland leaders, the library has a reading room.Today was the pilot launch of an automated reading room visitors' accounting system! The scanner of the system is installed at the entrance to the reading room. It records the events of the form ""reader entered room"", ""reader left room"". Every reader is assigned a registration number during the registration procedure at the library — it's a unique integer from 1 to 106. Thus, the system logs events of two forms:  ""+ ri"" — the reader with registration number ri entered the room;  ""- ri"" — the reader with registration number ri left the room. The first launch of the system was a success, it functioned for some period of time, and, at the time of its launch and at the time of its shutdown, the reading room may already have visitors.Significant funds of the budget of Berland have been spent on the design and installation of the system. Therefore, some of the citizens of the capital now demand to explain the need for this system and the benefits that its implementation will bring. Now, the developers of the system need to urgently come up with reasons for its existence.Help the system developers to find the minimum possible capacity of the reading room (in visitors) using the log of the system available to you.",[]446"T is a complete binary tree consisting of n vertices. It means that exactly one vertex is a root, and each vertex is either a leaf (and doesn't have children) or an inner node (and has exactly two children). All leaves of a complete binary tree have the same depth (distance from the root). So n is a number such that n + 1 is a power of 2.In the picture you can see a complete binary tree with n = 15.  Vertices are numbered from 1 to n in a special recursive way: we recursively assign numbers to all vertices from the left subtree (if current vertex is not a leaf), then assign a number to the current vertex, and then recursively assign numbers to all vertices from the right subtree (if it exists). In the picture vertices are numbered exactly using this algorithm. It is clear that for each size of a complete binary tree exists exactly one way to give numbers to all vertices. This way of numbering is called symmetric.You have to write a program that for given n answers q queries to the tree.Each query consists of an integer number ui (1 ≤ ui ≤ n) and a string si, where ui is the number of vertex, and si represents the path starting from this vertex. String si doesn't contain any characters other than 'L', 'R' and 'U', which mean traverse to the left child, to the right child and to the parent, respectively. Characters from si have to be processed from left to right, considering that ui is the vertex where the path starts. If it's impossible to process a character (for example, to go to the left child of a leaf), then you have to skip it. The answer is the number of vertex where the path represented by si ends.For example, if ui = 4 and si = «UURL», then the answer is 10.",['trees']447"Inaka has a disc, the circumference of which is $$$n$$$ units. The circumference is equally divided by $$$n$$$ points numbered clockwise from $$$1$$$ to $$$n$$$, such that points $$$i$$$ and $$$i + 1$$$ ($$$1 \leq i < n$$$) are adjacent, and so are points $$$n$$$ and $$$1$$$.There are $$$m$$$ straight segments on the disc, the endpoints of which are all among the aforementioned $$$n$$$ points.Inaka wants to know if her image is rotationally symmetrical, i.e. if there is an integer $$$k$$$ ($$$1 \leq k < n$$$), such that if all segments are rotated clockwise around the center of the circle by $$$k$$$ units, the new image will be the same as the original one.",['strings']448"There is a rectangular grid of size $$$n \times m$$$. Each cell of the grid is colored black ('0') or white ('1'). The color of the cell $$$(i, j)$$$ is $$$c_{i, j}$$$. You are also given a map of directions: for each cell, there is a direction $$$s_{i, j}$$$ which is one of the four characters 'U', 'R', 'D' and 'L'.  If $$$s_{i, j}$$$ is 'U' then there is a transition from the cell $$$(i, j)$$$ to the cell $$$(i - 1, j)$$$;  if $$$s_{i, j}$$$ is 'R' then there is a transition from the cell $$$(i, j)$$$ to the cell $$$(i, j + 1)$$$;  if $$$s_{i, j}$$$ is 'D' then there is a transition from the cell $$$(i, j)$$$ to the cell $$$(i + 1, j)$$$;  if $$$s_{i, j}$$$ is 'L' then there is a transition from the cell $$$(i, j)$$$ to the cell $$$(i, j - 1)$$$. It is guaranteed that the top row doesn't contain characters 'U', the bottom row doesn't contain characters 'D', the leftmost column doesn't contain characters 'L' and the rightmost column doesn't contain characters 'R'.You want to place some robots in this field (at most one robot in a cell). The following conditions should be satisfied.  Firstly, each robot should move every time (i.e. it cannot skip the move). During one move each robot goes to the adjacent cell depending on the current direction.  Secondly, you have to place robots in such a way that there is no move before which two different robots occupy the same cell (it also means that you cannot place two robots in the same cell). I.e. if the grid is ""RL"" (one row, two columns, colors does not matter there) then you can place two robots in cells $$$(1, 1)$$$ and $$$(1, 2)$$$, but if the grid is ""RLL"" then you cannot place robots in cells $$$(1, 1)$$$ and $$$(1, 3)$$$ because during the first second both robots will occupy the cell $$$(1, 2)$$$. The robots make an infinite number of moves.Your task is to place the maximum number of robots to satisfy all the conditions described above and among all such ways, you have to choose one where the number of black cells occupied by robots before all movements is the maximum possible. Note that you can place robots only before all movements.You have to answer $$$t$$$ independent test cases.",['graphs']449"The Two-dimensional kingdom is going through hard times... This morning the Three-Dimensional kingdom declared war on the Two-dimensional one. This (possibly armed) conflict will determine the ultimate owner of the straight line.The Two-dimensional kingdom has a regular army of n people. Each soldier registered himself and indicated the desired size of the bulletproof vest: the i-th soldier indicated size ai. The soldiers are known to be unpretentious, so the command staff assumes that the soldiers are comfortable in any vests with sizes from ai - x to ai + y, inclusive (numbers x, y ≥ 0 are specified). The Two-dimensional kingdom has m vests at its disposal, the j-th vest's size equals bj. Help mobilize the Two-dimensional kingdom's army: equip with vests as many soldiers as possible. Each vest can be used only once. The i-th soldier can put on the j-th vest, if ai - x ≤ bj ≤ ai + y.",[]450"Wilbur is playing with a set of n points on the coordinate plane. All points have non-negative integer coordinates. Moreover, if some point (x, y) belongs to the set, then all points (x', y'), such that 0 ≤ x' ≤ x and 0 ≤ y' ≤ y also belong to this set.Now Wilbur wants to number the points in the set he has, that is assign them distinct integer numbers from 1 to n. In order to make the numbering aesthetically pleasing, Wilbur imposes the condition that if some point (x, y) gets number i, then all (x',y') from the set, such that x' ≥ x and y' ≥ y must be assigned a number not less than i. For example, for a set of four points (0, 0), (0, 1), (1, 0) and (1, 1), there are two aesthetically pleasing numberings. One is 1, 2, 3, 4 and another one is 1, 3, 2, 4.Wilbur's friend comes along and challenges Wilbur. For any point he defines it's special value as s(x, y) = y - x. Now he gives Wilbur some w1, w2,..., wn, and asks him to find an aesthetically pleasing numbering of the points in the set, such that the point that gets number i has it's special value equal to wi, that is s(xi, yi) = yi - xi = wi.Now Wilbur asks you to help him with this challenge.",[]451"You have an array $$$a_1,a_2, \dots, a_n$$$. Each element initially has value $$$0$$$ and color $$$1$$$. You are also given $$$q$$$ queries to perform:   Color $$$l$$$ $$$r$$$ $$$c$$$: Change the color of elements $$$a_l,a_{l+1},\cdots,a_r$$$ to $$$c$$$ ($$$1 \le l \le r \le n$$$, $$$1 \le c \le n$$$).  Add $$$c$$$ $$$x$$$: Add $$$x$$$ to values of all elements $$$a_i$$$ ($$$1 \le i \le n$$$) of color $$$c$$$ ($$$1 \le c \le n$$$, $$$-10^9 \le x \le 10^9$$$).  Query $$$i$$$: Print $$$a_i$$$ ($$$1 \le i \le n$$$). ",[]452"You have multiset of n strings of the same length, consisting of lowercase English letters. We will say that those strings are easy to remember if for each string there is some position i and some letter c of the English alphabet, such that this string is the only string in the multiset that has letter c in position i.For example, a multiset of strings {""abc"", ""aba"", ""adc"", ""ada""} are not easy to remember. And multiset {""abc"", ""ada"", ""ssa""} is easy to remember because:   the first string is the only string that has character c in position 3;  the second string is the only string that has character d in position 2;  the third string is the only string that has character s in position 2. You want to change your multiset a little so that it is easy to remember. For aij coins, you can change character in the j-th position of the i-th string into any other lowercase letter of the English alphabet. Find what is the minimum sum you should pay in order to make the multiset of strings easy to remember.",[]453"Vasya is reading a e-book. The file of the book consists of $$$n$$$ pages, numbered from $$$1$$$ to $$$n$$$. The screen is currently displaying the contents of page $$$x$$$, and Vasya wants to read the page $$$y$$$. There are two buttons on the book which allow Vasya to scroll $$$d$$$ pages forwards or backwards (but he cannot scroll outside the book). For example, if the book consists of $$$10$$$ pages, and $$$d = 3$$$, then from the first page Vasya can scroll to the first or to the fourth page by pressing one of the buttons; from the second page — to the first or to the fifth; from the sixth page — to the third or to the ninth; from the eighth — to the fifth or to the tenth.Help Vasya to calculate the minimum number of times he needs to press a button to move to page $$$y$$$.",['math']454"You are given $$$n$$$ integers. You need to choose a subset and put the chosen numbers in a beautiful rectangle (rectangular matrix). Each chosen number should occupy one of its rectangle cells, each cell must be filled with exactly one chosen number. Some of the $$$n$$$ numbers may not be chosen.A rectangle (rectangular matrix) is called beautiful if in each row and in each column all values are different.What is the largest (by the total number of cells) beautiful rectangle you can construct? Print the rectangle itself.",['math']455"You have to handle a very complex water distribution system. The system consists of $$$n$$$ junctions and $$$m$$$ pipes, $$$i$$$-th pipe connects junctions $$$x_i$$$ and $$$y_i$$$.The only thing you can do is adjusting the pipes. You have to choose $$$m$$$ integer numbers $$$f_1$$$, $$$f_2$$$, ..., $$$f_m$$$ and use them as pipe settings. $$$i$$$-th pipe will distribute $$$f_i$$$ units of water per second from junction $$$x_i$$$ to junction $$$y_i$$$ (if $$$f_i$$$ is negative, then the pipe will distribute $$$|f_i|$$$ units of water per second from junction $$$y_i$$$ to junction $$$x_i$$$). It is allowed to set $$$f_i$$$ to any integer from $$$-2 \cdot 10^9$$$ to $$$2 \cdot 10^9$$$.In order for the system to work properly, there are some constraints: for every $$$i \in [1, n]$$$, $$$i$$$-th junction has a number $$$s_i$$$ associated with it meaning that the difference between incoming and outcoming flow for $$$i$$$-th junction must be exactly $$$s_i$$$ (if $$$s_i$$$ is not negative, then $$$i$$$-th junction must receive $$$s_i$$$ units of water per second; if it is negative, then $$$i$$$-th junction must transfer $$$|s_i|$$$ units of water per second to other junctions).Can you choose the integers $$$f_1$$$, $$$f_2$$$, ..., $$$f_m$$$ in such a way that all requirements on incoming and outcoming flows are satisfied?",['trees']456"Polycarp has a string $$$s$$$. Polycarp performs the following actions until the string $$$s$$$ is empty ($$$t$$$ is initially an empty string):  he adds to the right to the string $$$t$$$ the string $$$s$$$, i.e. he does $$$t = t + s$$$, where $$$t + s$$$ is a concatenation of the strings $$$t$$$ and $$$s$$$;  he selects an arbitrary letter of $$$s$$$ and removes from $$$s$$$ all its occurrences (the selected letter must occur in the string $$$s$$$ at the moment of performing this action). Polycarp performs this sequence of actions strictly in this order.Note that after Polycarp finishes the actions, the string $$$s$$$ will be empty and the string $$$t$$$ will be equal to some value (that is undefined and depends on the order of removing).E.g. consider $$$s$$$=""abacaba"" so the actions may be performed as follows:  $$$t$$$=""abacaba"", the letter 'b' is selected, then $$$s$$$=""aacaa"";  $$$t$$$=""abacabaaacaa"", the letter 'a' is selected, then $$$s$$$=""c"";  $$$t$$$=""abacabaaacaac"", the letter 'c' is selected, then $$$s$$$="""" (the empty string). You need to restore the initial value of the string $$$s$$$ using only the final value of $$$t$$$ and find the order of removing letters from $$$s$$$.",['strings']457"Several days ago you bought a new house and now you are planning to start a renovation. Since winters in your region can be very cold you need to decide how to heat rooms in your house.Your house has $$$n$$$ rooms. In the $$$i$$$-th room you can install at most $$$c_i$$$ heating radiators. Each radiator can have several sections, but the cost of the radiator with $$$k$$$ sections is equal to $$$k^2$$$ burles.Since rooms can have different sizes, you calculated that you need at least $$$sum_i$$$ sections in total in the $$$i$$$-th room. For each room calculate the minimum cost to install at most $$$c_i$$$ radiators with total number of sections not less than $$$sum_i$$$.",['math']458"Cat Furrier Transform is a popular algorithm among cat programmers to create longcats. As one of the greatest cat programmers ever exist, Neko wants to utilize this algorithm to create the perfect longcat.Assume that we have a cat with a number $$$x$$$. A perfect longcat is a cat with a number equal $$$2^m - 1$$$ for some non-negative integer $$$m$$$. For example, the numbers $$$0$$$, $$$1$$$, $$$3$$$, $$$7$$$, $$$15$$$ and so on are suitable for the perfect longcats.In the Cat Furrier Transform, the following operations can be performed on $$$x$$$:  (Operation A): you select any non-negative integer $$$n$$$ and replace $$$x$$$ with $$$x \oplus (2^n - 1)$$$, with $$$\oplus$$$ being a bitwise XOR operator. (Operation B): replace $$$x$$$ with $$$x + 1$$$. The first applied operation must be of type A, the second of type B, the third of type A again, and so on. Formally, if we number operations from one in the order they are executed, then odd-numbered operations must be of type A and the even-numbered operations must be of type B.Neko wants to produce perfect longcats at industrial scale, thus for each cat Neko only wants to perform at most $$$40$$$ operations. Can you help Neko writing a transformation plan?Note that it is not required to minimize the number of operations. You just need to use no more than $$$40$$$ operations.",['math']459"Berland State University has received a new update for the operating system. Initially it is installed only on the $$$1$$$-st computer.Update files should be copied to all $$$n$$$ computers. The computers are not connected to the internet, so the only way to transfer update files from one computer to another is to copy them using a patch cable (a cable connecting two computers directly). Only one patch cable can be connected to a computer at a time. Thus, from any computer where the update files are installed, they can be copied to some other computer in exactly one hour.Your task is to find the minimum number of hours required to copy the update files to all $$$n$$$ computers if there are only $$$k$$$ patch cables in Berland State University.",['math']460"A newspaper is published in Walrusland. Its heading is s1, it consists of lowercase Latin letters. Fangy the little walrus wants to buy several such newspapers, cut out their headings, glue them one to another in order to get one big string. After that walrus erase several letters from this string in order to get a new word s2. It is considered that when Fangy erases some letter, there's no whitespace formed instead of the letter. That is, the string remains unbroken and it still only consists of lowercase Latin letters.For example, the heading is ""abc"". If we take two such headings and glue them one to the other one, we get ""abcabc"". If we erase the letters on positions 1 and 5, we get a word ""bcac"".Which least number of newspaper headings s1 will Fangy need to glue them, erase several letters and get word s2?",['strings']461"You are given a string $$$t$$$ consisting of $$$n$$$ lowercase Latin letters and an integer number $$$k$$$.Let's define a substring of some string $$$s$$$ with indices from $$$l$$$ to $$$r$$$ as $$$s[l \dots r]$$$.Your task is to construct such string $$$s$$$ of minimum possible length that there are exactly $$$k$$$ positions $$$i$$$ such that $$$s[i \dots i + n - 1] = t$$$. In other words, your task is to construct such string $$$s$$$ of minimum possible length that there are exactly $$$k$$$ substrings of $$$s$$$ equal to $$$t$$$.It is guaranteed that the answer is always unique.",['strings']462"A MIPT student named Misha has a birthday today, and he decided to celebrate it in his country house in suburban Moscow. n friends came by, and after a typical party they decided to play blind man's buff.The birthday boy gets blindfolded and the other players scatter around the house. The game is played in several rounds. In each round, Misha catches exactly one of his friends and has to guess who it is. The probability of catching the i-th friend does not change between rounds and is equal to pi percent (as we know, it is directly proportional to the amount of alcohol consumed by the i-th friend) and p1 + p2 + ... + pn = 100 holds. Misha has no information about who he caught. After Misha makes an attempt to guess the caught person, the round ends. Even then, Misha isn't told whether he guessed correctly, and a new round begins.The game ends when Misha guesses every friend at least once, that is, there exists such set of rounds k1, k2, ..., kn, that during round number ki Misha caught the i-th friend and guessed him. Misha wants to minimize the expectation of the number of rounds of the game. Despite the fact that at any point in the game Misha has no information about who he has already guessed, his friends are honest, and if they see that the condition for the end of the game is fulfilled, the game ends immediately. Find the expectation of the number of rounds in the game if Misha plays optimally.","['math', 'probabilities']"463"Polycarp got an array of integers $$$a[1 \dots n]$$$ as a gift. Now he wants to perform a certain number of operations (possibly zero) so that all elements of the array become the same (that is, to become $$$a_1=a_2=\dots=a_n$$$). In one operation, he can take some indices in the array and increase the elements of the array at those indices by $$$1$$$.For example, let $$$a=[4,2,1,6,2]$$$. He can perform the following operation: select indices 1, 2, and 4 and increase elements of the array in those indices by $$$1$$$. As a result, in one operation, he can get a new state of the array $$$a=[5,3,1,7,2]$$$.What is the minimum number of operations it can take so that all elements of the array become equal to each other (that is, to become $$$a_1=a_2=\dots=a_n$$$)?",['math']464"Vasya has a beautiful garden where wonderful fruit trees grow and yield fantastic harvest every year. But lately thieves started to sneak into the garden at nights and steal the fruit too often. Vasya can’t spend the nights in the garden and guard the fruit because there’s no house in the garden! Vasya had been saving in for some time and finally he decided to build the house. The rest is simple: he should choose in which part of the garden to build the house. In the evening he sat at his table and drew the garden’s plan. On the plan the garden is represented as a rectangular checkered field n × m in size divided into squares whose side length is 1. In some squares Vasya marked the trees growing there (one shouldn’t plant the trees too close to each other that’s why one square contains no more than one tree). Vasya wants to find a rectangular land lot a × b squares in size to build a house on, at that the land lot border should go along the lines of the grid that separates the squares. All the trees that grow on the building lot will have to be chopped off. Vasya loves his garden very much, so help him choose the building land lot location so that the number of chopped trees would be as little as possible.",[]465"While Grisha was celebrating New Year with Ded Moroz, Misha gifted Sasha a small rectangular pond of size n × m, divided into cells of size 1 × 1, inhabited by tiny evil fishes (no more than one fish per cell, otherwise they'll strife!).The gift bundle also includes a square scoop of size r × r, designed for fishing. If the lower-left corner of the scoop-net is located at cell (x, y), all fishes inside the square (x, y)...(x + r - 1, y + r - 1) get caught. Note that the scoop-net should lie completely inside the pond when used.Unfortunately, Sasha is not that skilled in fishing and hence throws the scoop randomly. In order to not frustrate Sasha, Misha decided to release k fishes into the empty pond in such a way that the expected value of the number of caught fishes is as high as possible. Help Misha! In other words, put k fishes in the pond into distinct cells in such a way that when the scoop-net is placed into a random position among (n - r + 1)·(m - r + 1) possible positions, the average number of caught fishes is as high as possible.","['graphs', 'probabilities']"466"For a sequence of strings $$$[t_1, t_2, \dots, t_m]$$$, let's define the function $$$f([t_1, t_2, \dots, t_m])$$$ as the number of different strings (including the empty string) that are subsequences of at least one string $$$t_i$$$. $$$f([]) = 0$$$ (i. e. the number of such strings for an empty sequence is $$$0$$$).You are given a sequence of strings $$$[s_1, s_2, \dots, s_n]$$$. Every string in this sequence consists of lowercase Latin letters and is sorted (i. e., each string begins with several (maybe zero) characters a, then several (maybe zero) characters b, ..., ends with several (maybe zero) characters z).For each of $$$2^n$$$ subsequences of $$$[s_1, s_2, \dots, s_n]$$$, calculate the value of the function $$$f$$$ modulo $$$998244353$$$.",[]467"Vasya is currently at a car rental service, and he wants to reach cinema. The film he has bought a ticket for starts in t minutes. There is a straight road of length s from the service to the cinema. Let's introduce a coordinate system so that the car rental service is at the point 0, and the cinema is at the point s.There are k gas stations along the road, and at each of them you can fill a car with any amount of fuel for free! Consider that this operation doesn't take any time, i.e. is carried out instantly.There are n cars in the rental service, i-th of them is characterized with two integers ci and vi — the price of this car rent and the capacity of its fuel tank in liters. It's not allowed to fuel a car with more fuel than its tank capacity vi. All cars are completely fueled at the car rental service.Each of the cars can be driven in one of two speed modes: normal or accelerated. In the normal mode a car covers 1 kilometer in 2 minutes, and consumes 1 liter of fuel. In the accelerated mode a car covers 1 kilometer in 1 minutes, but consumes 2 liters of fuel. The driving mode can be changed at any moment and any number of times.Your task is to choose a car with minimum price such that Vasya can reach the cinema before the show starts, i.e. not later than in t minutes. Assume that all cars are completely fueled initially.",[]468"Now it's time of Olympiads. Vanya and Egor decided to make his own team to take part in a programming Olympiad. They've been best friends ever since primary school and hopefully, that can somehow help them in teamwork.For each team Olympiad, Vanya takes his play cards with numbers. He takes only the cards containing numbers 1 and 0. The boys are very superstitious. They think that they can do well at the Olympiad if they begin with laying all the cards in a row so that:  there wouldn't be a pair of any side-adjacent cards with zeroes in a row;  there wouldn't be a group of three consecutive cards containing numbers one. Today Vanya brought n cards with zeroes and m cards with numbers one. The number of cards was so much that the friends do not know how to put all those cards in the described way. Help them find the required arrangement of the cards or else tell the guys that it is impossible to arrange cards in such a way.",[]469"Egor came up with a new chips puzzle and suggests you to play.The puzzle has the form of a table with $$$n$$$ rows and $$$m$$$ columns, each cell can contain several black or white chips placed in a row. Thus, the state of the cell can be described by a string consisting of characters '0' (a white chip) and '1' (a black chip), possibly empty, and the whole puzzle can be described as a table, where each cell is a string of zeros and ones. The task is to get from one state of the puzzle some other state.To do this, you can use the following operation.  select 2 different cells $$$(x_1, y_1)$$$ and $$$(x_2, y_2)$$$: the cells must be in the same row or in the same column of the table, and the string in the cell $$$(x_1, y_1)$$$ must be non-empty;  in one operation you can move the last character of the string at the cell $$$(x_1, y_1)$$$ to the beginning of the string at the cell $$$(x_2, y_2)$$$. Egor came up with two states of the table for you: the initial state and the final one. It is guaranteed that the number of zeros and ones in the tables are the same. Your goal is with several operations get the final state from the initial state. Of course, Egor does not want the number of operations to be very large. Let's denote as $$$s$$$ the number of characters in each of the tables (which are the same). Then you should use no more than $$$4 \cdot s$$$ operations.",['math']470"The store sells $$$n$$$ beads. The color of each bead is described by a lowercase letter of the English alphabet (""a""–""z""). You want to buy some beads to assemble a necklace from them.A necklace is a set of beads connected in a circle.For example, if the store sells beads ""a"", ""b"", ""c"", ""a"", ""c"", ""c"", then you can assemble the following necklaces (these are not all possible options):  And the following necklaces cannot be assembled from beads sold in the store:  The first necklace cannot be assembled because it has three beads ""a"" (of the two available). The second necklace cannot be assembled because it contains a bead ""d"", which is not sold in the store. We call a necklace $$$k$$$-beautiful if, when it is turned clockwise by $$$k$$$ beads, the necklace remains unchanged. For example, here is a sequence of three turns of a necklace.    As you can see, this necklace is, for example, $$$3$$$-beautiful, $$$6$$$-beautiful, $$$9$$$-beautiful, and so on, but it is not $$$1$$$-beautiful or $$$2$$$-beautiful.In particular, a necklace of length $$$1$$$ is $$$k$$$-beautiful for any integer $$$k$$$. A necklace that consists of beads of the same color is also beautiful for any $$$k$$$.You are given the integers $$$n$$$ and $$$k$$$, and also the string $$$s$$$ containing $$$n$$$ lowercase letters of the English alphabet — each letter defines a bead in the store. You can buy any subset of beads and connect them in any order. Find the maximum length of a $$$k$$$-beautiful necklace you can assemble.","['graphs', 'number theory']"471"Stanley lives in a country that consists of $$$n$$$ cities (he lives in city $$$1$$$). There are bidirectional roads between some of the cities, and you know how long it takes to ride through each of them. Additionally, there is a flight between each pair of cities, the flight between cities $$$u$$$ and $$$v$$$ takes $$$(u - v)^2$$$ time.Stanley is quite afraid of flying because of watching ""Sully: Miracle on the Hudson"" recently, so he can take at most $$$k$$$ flights. Stanley wants to know the minimum time of a journey to each of the $$$n$$$ cities from the city $$$1$$$.","['graphs', 'geometry']"472"An important meeting is to be held and there are exactly $$$n$$$ people invited. At any moment, any two people can step back and talk in private. The same two people can talk several (as many as they want) times per meeting.Each person has limited sociability. The sociability of the $$$i$$$-th person is a non-negative integer $$$a_i$$$. This means that after exactly $$$a_i$$$ talks this person leaves the meeting (and does not talk to anyone else anymore). If $$$a_i = 0$$$, the $$$i$$$-th person leaves the meeting immediately after it starts.A meeting is considered most productive if the maximum possible number of talks took place during it.You are given an array of sociability $$$a$$$, determine which people should talk to each other so that the total number of talks is as large as possible.",['graphs']473"As you very well know, the whole Universe traditionally uses three-dimensional Cartesian system of coordinates. In this system each point corresponds to three real coordinates (x, y, z). In this coordinate system, the distance between the center of the Universe and the point is calculated by the following formula: . Mushroom scientists that work for the Great Mushroom King think that the Universe isn't exactly right and the distance from the center of the Universe to a point equals xa·yb·zc.To test the metric of mushroom scientists, the usual scientists offered them a task: find such x, y, z (0 ≤ x, y, z; x + y + z ≤ S), that the distance between the center of the Universe and the point (x, y, z) is maximum possible in the metric of mushroom scientists. The mushroom scientists aren't good at maths, so they commissioned you to do the task.Note that in this problem, it is considered that 00 = 1.",['math']474"Polycarp loves geometric progressions — he collects them. However, as such progressions occur very rarely, he also loves the sequences of numbers where it is enough to delete a single element to get a geometric progression.In this task we shall define geometric progressions as finite sequences of numbers a1, a2, ..., ak, where ai = c·bi - 1 for some real numbers c and b. For example, the sequences [2, -4, 8], [0, 0, 0, 0], [199] are geometric progressions and [0, 1, 2, 3] is not.Recently Polycarp has found a sequence and he can't classify it. Help him to do it. Determine whether it is a geometric progression. If it is not, check if it can become a geometric progression if an element is deleted from it.",[]475"A permutation of length n is an integer sequence such that each integer from 0 to (n - 1) appears exactly once in it. For example, sequence [0, 2, 1] is a permutation of length 3 while both [0, 2, 2] and [1, 2, 3] are not.A fixed point of a function is a point that is mapped to itself by the function. A permutation can be regarded as a bijective function. We'll get a definition of a fixed point in a permutation. An integer i is a fixed point of permutation a0, a1, ..., an - 1 if and only if ai = i. For example, permutation [0, 2, 1] has 1 fixed point and permutation [0, 1, 2] has 3 fixed points.You are given permutation a. You are allowed to swap two elements of the permutation at most once. Your task is to maximize the number of fixed points in the resulting permutation. Note that you are allowed to make at most one swap operation.",['math']476"You have an array of positive integers a[1], a[2], ..., a[n] and a set of bad prime numbers b1, b2, ..., bm. The prime numbers that do not occur in the set b are considered good. The beauty of array a is the sum , where function f(s) is determined as follows:  f(1) = 0;  Let's assume that p is the minimum prime divisor of s. If p is a good prime, then , otherwise . You are allowed to perform an arbitrary (probably zero) number of operations to improve array a. The operation of improvement is the following sequence of actions:  Choose some number r (1 ≤ r ≤ n) and calculate the value g = GCD(a[1], a[2], ..., a[r]).  Apply the assignments: , , ..., . What is the maximum beauty of the array you can get? ","['math', 'number theory']"477"Consider a sequence of digits of length $$$2^k$$$ $$$[a_1, a_2, \ldots, a_{2^k}]$$$. We perform the following operation with it: replace pairs $$$(a_{2i+1}, a_{2i+2})$$$ with $$$(a_{2i+1} + a_{2i+2})\bmod 10$$$ for $$$0\le i<2^{k-1}$$$. For every $$$i$$$ where $$$a_{2i+1} + a_{2i+2}\ge 10$$$ we get a candy! As a result, we will get a sequence of length $$$2^{k-1}$$$.Less formally, we partition sequence of length $$$2^k$$$ into $$$2^{k-1}$$$ pairs, each consisting of 2 numbers: the first pair consists of the first and second numbers, the second of the third and fourth $$$\ldots$$$, the last pair consists of the ($$$2^k-1$$$)-th and ($$$2^k$$$)-th numbers. For every pair such that sum of numbers in it is at least $$$10$$$, we get a candy. After that, we replace every pair of numbers with a remainder of the division of their sum by $$$10$$$ (and don't change the order of the numbers).Perform this operation with a resulting array until it becomes of length $$$1$$$. Let $$$f([a_1, a_2, \ldots, a_{2^k}])$$$ denote the number of candies we get in this process. For example: if the starting sequence is $$$[8, 7, 3, 1, 7, 0, 9, 4]$$$ then:After the first operation the sequence becomes $$$[(8 + 7)\bmod 10, (3 + 1)\bmod 10, (7 + 0)\bmod 10, (9 + 4)\bmod 10]$$$ $$$=$$$ $$$[5, 4, 7, 3]$$$, and we get $$$2$$$ candies as $$$8 + 7 \ge 10$$$ and $$$9 + 4 \ge 10$$$.After the second operation the sequence becomes $$$[(5 + 4)\bmod 10, (7 + 3)\bmod 10]$$$ $$$=$$$ $$$[9, 0]$$$, and we get one more candy as $$$7 + 3 \ge 10$$$. After the final operation sequence becomes $$$[(9 + 0) \bmod 10]$$$ $$$=$$$ $$$[9]$$$. Therefore, $$$f([8, 7, 3, 1, 7, 0, 9, 4]) = 3$$$ as we got $$$3$$$ candies in total.You are given a sequence of digits of length $$$n$$$ $$$s_1, s_2, \ldots s_n$$$. You have to answer $$$q$$$ queries of the form $$$(l_i, r_i)$$$, where for $$$i$$$-th query you have to output $$$f([s_{l_i}, s_{l_i+1}, \ldots, s_{r_i}])$$$. It is guaranteed that $$$r_i-l_i+1$$$ is of form $$$2^k$$$ for some nonnegative integer $$$k$$$.",['math']478"You're given an array $$$b$$$ of length $$$n$$$. Let's define another array $$$a$$$, also of length $$$n$$$, for which $$$a_i = 2^{b_i}$$$ ($$$1 \leq i \leq n$$$). Valerii says that every two non-intersecting subarrays of $$$a$$$ have different sums of elements. You want to determine if he is wrong. More formally, you need to determine if there exist four integers $$$l_1,r_1,l_2,r_2$$$ that satisfy the following conditions:   $$$1 \leq l_1 \leq r_1 \lt l_2 \leq r_2 \leq n$$$;  $$$a_{l_1}+a_{l_1+1}+\ldots+a_{r_1-1}+a_{r_1} = a_{l_2}+a_{l_2+1}+\ldots+a_{r_2-1}+a_{r_2}$$$. If such four integers exist, you will prove Valerii wrong. Do they exist?An array $$$c$$$ is a subarray of an array $$$d$$$ if $$$c$$$ can be obtained from $$$d$$$ by deletion of several (possibly, zero or all) elements from the beginning and several (possibly, zero or all) elements from the end.",[]479"My orzlers, we can optimize this problem from $$$O(S^3)$$$ to $$$O\left(T^\frac{5}{9}\right)$$$!— Spyofgame, founder of Orzlim religionA long time ago, Spyofgame invented the famous array $$$a$$$ ($$$1$$$-indexed) of length $$$n$$$ that contains information about the world and life. After that, he decided to convert it into the matrix $$$b$$$ ($$$0$$$-indexed) of size $$$(n + 1) \times (n + 1)$$$ which contains information about the world, life and beyond.Spyofgame converted $$$a$$$ into $$$b$$$ with the following rules.  $$$b_{i,0} = 0$$$ if $$$0 \leq i \leq n$$$;  $$$b_{0,i} = a_{i}$$$ if $$$1 \leq i \leq n$$$;  $$$b_{i,j} = b_{i,j-1} \oplus b_{i-1,j}$$$ if $$$1 \leq i, j \leq n$$$. Here $$$\oplus$$$ denotes the bitwise XOR operation.Today, archaeologists have discovered the famous matrix $$$b$$$. However, many elements of the matrix has been lost. They only know the values of $$$b_{i,n}$$$ for $$$1 \leq i \leq n$$$ (note that these are some elements of the last column, not the last row).The archaeologists want to know what a possible array of $$$a$$$ is. Can you help them reconstruct any array that could be $$$a$$$?",['math']480"This is the easy version of the problem. The difference between the versions is that the easy version does not require you to output the numbers of the rods to be removed. You can make hacks only if all versions of the problem are solved.Stitch likes experimenting with different machines with his friend Sparky. Today they built another machine.The main element of this machine are $$$n$$$ rods arranged along one straight line and numbered from $$$1$$$ to $$$n$$$ inclusive. Each of these rods must carry an electric charge quantitatively equal to either $$$1$$$ or $$$-1$$$ (otherwise the machine will not work). Another condition for this machine to work is that the sign-variable sum of the charge on all rods must be zero.More formally, the rods can be represented as an array of $$$n$$$ numbers characterizing the charge: either $$$1$$$ or $$$-1$$$. Then the condition must hold: $$$a_1 - a_2 + a_3 - a_4 + \ldots = 0$$$, or $$$\sum\limits_{i=1}^n (-1)^{i-1} \cdot a_i = 0$$$.Sparky charged all $$$n$$$ rods with an electric current, but unfortunately it happened that the rods were not charged correctly (the sign-variable sum of the charge is not zero). The friends decided to leave only some of the rods in the machine. Sparky has $$$q$$$ questions. In the $$$i$$$th question Sparky asks: if the machine consisted only of rods with numbers $$$l_i$$$ to $$$r_i$$$ inclusive, what minimal number of rods could be removed from the machine so that the sign-variable sum of charges on the remaining ones would be zero? Perhaps the friends got something wrong, and the sign-variable sum is already zero. In that case, you don't have to remove the rods at all.If the number of rods is zero, we will assume that the sign-variable sum of charges is zero, that is, we can always remove all rods.Help your friends and answer all of Sparky's questions!",['math']481"This is an interactive problem.We hid from you a permutation $$$p$$$ of length $$$n$$$, consisting of the elements from $$$1$$$ to $$$n$$$. You want to guess it. To do that, you can give us 2 different indices $$$i$$$ and $$$j$$$, and we will reply with $$$p_{i} \bmod p_{j}$$$ (remainder of division $$$p_{i}$$$ by $$$p_{j}$$$).We have enough patience to answer at most $$$2 \cdot n$$$ queries, so you should fit in this constraint. Can you do it?As a reminder, a permutation of length $$$n$$$ is an array consisting of $$$n$$$ distinct integers from $$$1$$$ to $$$n$$$ in arbitrary order. For example, $$$[2,3,1,5,4]$$$ is a permutation, but $$$[1,2,2]$$$ is not a permutation ($$$2$$$ appears twice in the array) and $$$[1,3,4]$$$ is also not a permutation ($$$n=3$$$ but there is $$$4$$$ in the array).",['math']482"You are given a permutation $$$a_1, a_2, \ldots, a_n$$$ of size $$$n$$$, where each integer from $$$1$$$ to $$$n$$$ appears exactly once.You can do the following operation any number of times (possibly, zero):  Choose any three indices $$$i, j, k$$$ ($$$1 \le i < j < k \le n$$$).  If $$$a_i > a_k$$$, replace $$$a_i$$$ with $$$a_i + a_j$$$. Otherwise, swap $$$a_j$$$ and $$$a_k$$$. Determine whether you can make the array $$$a$$$ sorted in non-descending order.",['math']483"You are given a string $$$s$$$ consisting of $$$n$$$ lowercase Latin letters. Polycarp wants to remove exactly $$$k$$$ characters ($$$k \le n$$$) from the string $$$s$$$. Polycarp uses the following algorithm $$$k$$$ times:  if there is at least one letter 'a', remove the leftmost occurrence and stop the algorithm, otherwise go to next item;  if there is at least one letter 'b', remove the leftmost occurrence and stop the algorithm, otherwise go to next item;  ...  remove the leftmost occurrence of the letter 'z' and stop the algorithm. This algorithm removes a single letter from the string. Polycarp performs this algorithm exactly $$$k$$$ times, thus removing exactly $$$k$$$ characters.Help Polycarp find the resulting string.",[]484"Given a string s, determine if it contains any palindrome of length exactly 100 as a subsequence. If it has any, print any one of them. If it doesn't have any, print a palindrome that is a subsequence of s and is as long as possible.",[]485"Bike loves looking for the second maximum element in the sequence. The second maximum element in the sequence of distinct numbers x1, x2, ..., xk (k > 1) is such maximum element xj, that the following inequality holds: .The lucky number of the sequence of distinct positive integers x1, x2, ..., xk (k > 1) is the number that is equal to the bitwise excluding OR of the maximum element of the sequence and the second maximum element of the sequence.You've got a sequence of distinct positive integers s1, s2, ..., sn (n > 1). Let's denote sequence sl, sl + 1, ..., sr as s[l..r] (1 ≤ l < r ≤ n). Your task is to find the maximum number among all lucky numbers of sequences s[l..r].Note that as all numbers in sequence s are distinct, all the given definitions make sence.",[]486"Little Chris knows there's no fun in playing dominoes, he thinks it's too random and doesn't require skill. Instead, he decided to play with the dominoes and make a ""domino show"".Chris arranges n dominoes in a line, placing each piece vertically upright. In the beginning, he simultaneously pushes some of the dominoes either to the left or to the right. However, somewhere between every two dominoes pushed in the same direction there is at least one domino pushed in the opposite direction.After each second, each domino that is falling to the left pushes the adjacent domino on the left. Similarly, the dominoes falling to the right push their adjacent dominoes standing on the right. When a vertical domino has dominoes falling on it from both sides, it stays still due to the balance of the forces. The figure shows one possible example of the process.  Given the initial directions Chris has pushed the dominoes, find the number of the dominoes left standing vertically at the end of the process!",[]487"Roma works in a company that sells TVs. Now he has to prepare a report for the last year.Roma has got a list of the company's incomes. The list is a sequence that consists of n integers. The total income of the company is the sum of all integers in sequence. Roma decided to perform exactly k changes of signs of several numbers in the sequence. He can also change the sign of a number one, two or more times.The operation of changing a number's sign is the operation of multiplying this number by -1.Help Roma perform the changes so as to make the total income of the company (the sum of numbers in the resulting sequence) maximum. Note that Roma should perform exactly k changes.",[]488"A boy Petya loves chess very much. He even came up with a chess piece of his own, a semiknight. The semiknight can move in any of these four directions: 2 squares forward and 2 squares to the right, 2 squares forward and 2 squares to the left, 2 squares backward and 2 to the right and 2 squares backward and 2 to the left. Naturally, the semiknight cannot move beyond the limits of the chessboard.Petya put two semiknights on a standard chessboard. Petya simultaneously moves with both semiknights. The squares are rather large, so after some move the semiknights can meet, that is, they can end up in the same square. After the meeting the semiknights can move on, so it is possible that they meet again. Petya wonders if there is such sequence of moves when the semiknights meet. Petya considers some squares bad. That is, they do not suit for the meeting. The semiknights can move through these squares but their meetings in these squares don't count.Petya prepared multiple chess boards. Help Petya find out whether the semiknights can meet on some good square for each board.Please see the test case analysis.",['math']489"One player came to a casino and found a slot machine where everything depends only on how he plays. The rules follow.A positive integer $$$a$$$ is initially on the screen. The player can put a coin into the machine and then add $$$1$$$ to or subtract $$$1$$$ from any two adjacent digits. All digits must remain from $$$0$$$ to $$$9$$$ after this operation, and the leading digit must not equal zero. In other words, it is forbidden to add $$$1$$$ to $$$9$$$, to subtract $$$1$$$ from $$$0$$$ and to subtract $$$1$$$ from the leading $$$1$$$. Once the number on the screen becomes equal to $$$b$$$, the player wins the jackpot. $$$a$$$ and $$$b$$$ have the same number of digits.Help the player to determine the minimal number of coins he needs to spend in order to win the jackpot and tell how to play.",['math']490"Everyone knows that agents in Valorant decide, who will play as attackers, and who will play as defenders. To do that Raze and Breach decided to play $$$t$$$ matches of a digit game...In each of $$$t$$$ matches of the digit game, a positive integer is generated. It consists of $$$n$$$ digits. The digits of this integer are numerated from $$$1$$$ to $$$n$$$ from the highest-order digit to the lowest-order digit. After this integer is announced, the match starts.Agents play in turns. Raze starts. In one turn an agent can choose any unmarked digit and mark it. Raze can choose digits on odd positions, but can not choose digits on even positions. Breach can choose digits on even positions, but can not choose digits on odd positions. The match ends, when there is only one unmarked digit left. If the single last digit is odd, then Raze wins, else Breach wins.It can be proved, that before the end of the match (for every initial integer with $$$n$$$ digits) each agent has an ability to make a turn, i.e. there is at least one unmarked digit, that stands on a position of required parity.For each of $$$t$$$ matches find out, which agent wins, if both of them want to win and play optimally.",['games']491"You wrote down all integers from $$$0$$$ to $$$10^n - 1$$$, padding them with leading zeroes so their lengths are exactly $$$n$$$. For example, if $$$n = 3$$$ then you wrote out 000, 001, ..., 998, 999.A block in an integer $$$x$$$ is a consecutive segment of equal digits that cannot be extended to the left or to the right.For example, in the integer $$$00027734000$$$ there are three blocks of length $$$1$$$, one block of length $$$2$$$ and two blocks of length $$$3$$$.For all integers $$$i$$$ from $$$1$$$ to $$$n$$$ count the number of blocks of length $$$i$$$ among the written down integers.Since these integers may be too large, print them modulo $$$998244353$$$.",['math']492"Bash likes playing with arrays. He has an array a1, a2, ... an of n integers. He likes to guess the greatest common divisor (gcd) of different segments of the array. Of course, sometimes the guess is not correct. However, Bash will be satisfied if his guess is almost correct.Suppose he guesses that the gcd of the elements in the range [l, r] of a is x. He considers the guess to be almost correct if he can change at most one element in the segment such that the gcd of the segment is x after making the change. Note that when he guesses, he doesn't actually change the array — he just wonders if the gcd of the segment can be made x. Apart from this, he also sometimes makes changes to the array itself.Since he can't figure it out himself, Bash wants you to tell him which of his guesses are almost correct. Formally, you have to process q queries of one of the following forms:  1 l r x — Bash guesses that the gcd of the range [l, r] is x. Report if this guess is almost correct.  2 i y — Bash sets ai to y. Note: The array is 1-indexed.",['number theory']493"The teacher gave Anton a large geometry homework, but he didn't do it (as usual) as he participated in a regular round on Codeforces. In the task he was given a set of n lines defined by the equations y = ki·x + bi. It was necessary to determine whether there is at least one point of intersection of two of these lines, that lays strictly inside the strip between x1 < x2. In other words, is it true that there are 1 ≤ i < j ≤ n and x', y', such that:   y' = ki * x' + bi, that is, point (x', y') belongs to the line number i;  y' = kj * x' + bj, that is, point (x', y') belongs to the line number j;  x1 < x' < x2, that is, point (x', y') lies inside the strip bounded by x1 < x2. You can't leave Anton in trouble, can you? Write a program that solves the given task.",['geometry']494"Немногие знают, что сотрудники ВКонтакте могут менять цвет подсветки в куполе знаменитого Дома Зингера, где расположена штаб-квартира ВКонтакте. Для этого нужно всего лишь отправить сообщение с цветом в специальный чат «Зингер | color», а бот его распознает и сменит подсветку. При этом на время городских мероприятий смена цвета блокируется.Формально, бот обрабатывает три типа сообщений:   lock: заблокировать изменение цвета. Если оно и так заблокировано на данный момент, сообщение игнорируется.  unlock: разблокировать изменение цвета. Если оно и так разблокировано на данный момент, сообщение игнорируется.  red / orange / yellow / green / blue / indigo / violet: изменить цвет купола на заданный, если изменение цвета на данный момент не заблокировано. Вам дана история сообщений, полученных ботом, в хронологическом порядке. Считайте, что перед получением первого сообщения купол подсвечивается голубым (blue), а изменение цвета не заблокировано.Определите, какой цвет будет у купола Дома Зингера после обработки этих сообщений.",[]495"Vasya claims that he had a paper square. He cut it into two rectangular parts using one vertical or horizontal cut. Then Vasya informed you the dimensions of these two rectangular parts. You need to check whether Vasya originally had a square. In other words, check if it is possible to make a square using two given rectangles.",['math']496"Berland has a long and glorious history. To increase awareness about it among younger citizens, King of Berland decided to compose an anthem.Though there are lots and lots of victories in history of Berland, there is the one that stand out the most. King wants to mention it in the anthem as many times as possible.He has already composed major part of the anthem and now just needs to fill in some letters. King asked you to help him with this work.The anthem is the string s of no more than 105 small Latin letters and question marks. The most glorious victory is the string t of no more than 105 small Latin letters. You should replace all the question marks with small Latin letters in such a way that the number of occurrences of string t in string s is maximal.Note that the occurrences of string t in s can overlap. Check the third example for clarification.",['strings']497"You play a computer game. Your character stands on some level of a multilevel ice cave. In order to move on forward, you need to descend one level lower and the only way to do this is to fall through the ice.The level of the cave where you are is a rectangular square grid of n rows and m columns. Each cell consists either from intact or from cracked ice. From each cell you can move to cells that are side-adjacent with yours (due to some limitations of the game engine you cannot make jumps on the same place, i.e. jump from a cell to itself). If you move to the cell with cracked ice, then your character falls down through it and if you move to the cell with intact ice, then the ice on this cell becomes cracked.Let's number the rows with integers from 1 to n from top to bottom and the columns with integers from 1 to m from left to right. Let's denote a cell on the intersection of the r-th row and the c-th column as (r, c). You are staying in the cell (r1, c1) and this cell is cracked because you've just fallen here from a higher level. You need to fall down through the cell (r2, c2) since the exit to the next level is there. Can you do this?",[]498"At first, there was a legend related to the name of the problem, but now it's just a formal statement.You are given $$$n$$$ points $$$a_1, a_2, \dots, a_n$$$ on the $$$OX$$$ axis. Now you are asked to find such an integer point $$$x$$$ on $$$OX$$$ axis that $$$f_k(x)$$$ is minimal possible.The function $$$f_k(x)$$$ can be described in the following way:   form a list of distances $$$d_1, d_2, \dots, d_n$$$ where $$$d_i = |a_i - x|$$$ (distance between $$$a_i$$$ and $$$x$$$);  sort list $$$d$$$ in non-descending order;  take $$$d_{k + 1}$$$ as a result. If there are multiple optimal answers you can print any of them.",[]499"Everybody knows that the $$$m$$$-coder Tournament will happen soon. $$$m$$$ schools participate in the tournament, and only one student from each school participates.There are a total of $$$n$$$ students in those schools. Before the tournament, all students put their names and the names of their schools into the Technogoblet of Fire. After that, Technogoblet selects the strongest student from each school to participate. Arkady is a hacker who wants to have $$$k$$$ Chosen Ones selected by the Technogoblet. Unfortunately, not all of them are the strongest in their schools, but Arkady can make up some new school names and replace some names from Technogoblet with those. You can't use each made-up name more than once. In that case, Technogoblet would select the strongest student in those made-up schools too.You know the power of each student and schools they study in. Calculate the minimal number of schools Arkady has to make up so that $$$k$$$ Chosen Ones would be selected by the Technogoblet.",[]500"«Bersoft» company is working on a new version of its most popular text editor — Bord 2010. Bord, like many other text editors, should be able to print out multipage documents. A user keys a sequence of the document page numbers that he wants to print out (separates them with a comma, without spaces).Your task is to write a part of the program, responsible for «standardization» of this sequence. Your program gets the sequence, keyed by the user, as input. The program should output this sequence in format l1-r1,l2-r2,...,lk-rk, where ri + 1 < li + 1 for all i from 1 to k - 1, and li ≤ ri. The new sequence should contain all the page numbers, keyed by the user, and nothing else. If some page number appears in the input sequence several times, its appearances, starting from the second one, should be ignored. If for some element i from the new sequence li = ri, this element should be output as li, and not as «li - li».For example, sequence 1,2,3,1,1,2,6,6,2 should be output as 1-3,6.",['strings']501"Let's call a set of positive integers $$$a_1, a_2, \dots, a_k$$$ quadratic if the product of the factorials of its elements is a square of an integer, i. e. $$$\prod\limits_{i=1}^{k} a_i! = m^2$$$, for some integer $$$m$$$.You are given a positive integer $$$n$$$.Your task is to find a quadratic subset of a set $$$1, 2, \dots, n$$$ of maximum size. If there are multiple answers, print any of them.","['math', 'number theory']"502"Hacker Zhorik wants to decipher two secret messages he intercepted yesterday. Yeah message is a sequence of encrypted blocks, each of them consists of several bytes of information.Zhorik knows that each of the messages is an archive containing one or more files. Zhorik knows how each of these archives was transferred through the network: if an archive consists of k files of sizes l1, l2, ..., lk bytes, then the i-th file is split to one or more blocks bi, 1, bi, 2, ..., bi, mi (here the total length of the blocks bi, 1 + bi, 2 + ... + bi, mi is equal to the length of the file li), and after that all blocks are transferred through the network, maintaining the order of files in the archive.Zhorik thinks that the two messages contain the same archive, because their total lengths are equal. However, each file can be split in blocks in different ways in the two messages.You are given the lengths of blocks in each of the two messages. Help Zhorik to determine what is the maximum number of files could be in the archive, if the Zhorik's assumption is correct.",[]503"The bear has a string s = s1s2... s|s| (record |s| is the string's length), consisting of lowercase English letters. The bear wants to count the number of such pairs of indices i, j (1 ≤ i ≤ j ≤ |s|), that string x(i, j) = sisi + 1... sj contains at least one string ""bear"" as a substring.String x(i, j) contains string ""bear"", if there is such index k (i ≤ k ≤ j - 3), that sk = b, sk + 1 = e, sk + 2 = a, sk + 3 = r.Help the bear cope with the given problem.","['math', 'strings']"504"You are given a rooted tree with n vertices. In each leaf vertex there's a single integer — the number of apples in this vertex. The weight of a subtree is the sum of all numbers in this subtree leaves. For instance, the weight of a subtree that corresponds to some leaf is the number written in the leaf.A tree is balanced if for every vertex v of the tree all its subtrees, corresponding to the children of vertex v, are of equal weight. Count the minimum number of apples that you need to remove from the tree (specifically, from some of its leaves) in order to make the tree balanced. Notice that you can always achieve the goal by just removing all apples.","['number theory', 'trees']"505"Monocarp has been collecting rare magazines for quite a while, and now he has decided to sell them. He distributed the magazines between $$$n$$$ boxes, arranged in a row. The $$$i$$$-th box contains $$$a_i$$$ magazines. Some of the boxes are covered with lids, others are not. Suddenly it started to rain, and now Monocarp has to save as many magazines from the rain as possible. To do this, he can move the lids between boxes as follows: if the $$$i$$$-th box was covered with a lid initially, he can either move the lid from the $$$i$$$-th box to the box $$$(i-1)$$$ (if it exists), or keep the lid on the $$$i$$$-th box. You may assume that Monocarp can move the lids instantly at the same moment, and no lid can be moved more than once. If a box will be covered with a lid after Monocarp moves the lids, the magazines in it will be safe from the rain; otherwise they will soak.You have to calculate the maximum number of magazines Monocarp can save from the rain.",[]506"Pavel made a photo of his favourite stars in the sky. His camera takes a photo of all points of the sky that belong to some rectangle with sides parallel to the coordinate axes.Strictly speaking, it makes a photo of all points with coordinates $$$(x, y)$$$, such that $$$x_1 \leq x \leq x_2$$$ and $$$y_1 \leq y \leq y_2$$$, where $$$(x_1, y_1)$$$ and $$$(x_2, y_2)$$$ are coordinates of the left bottom and the right top corners of the rectangle being photographed. The area of this rectangle can be zero.After taking the photo, Pavel wrote down coordinates of $$$n$$$ of his favourite stars which appeared in the photo. These points are not necessarily distinct, there can be multiple stars in the same point of the sky.Pavel has lost his camera recently and wants to buy a similar one. Specifically, he wants to know the dimensions of the photo he took earlier. Unfortunately, the photo is also lost. His notes are also of not much help; numbers are written in random order all over his notepad, so it's impossible to tell which numbers specify coordinates of which points.Pavel asked you to help him to determine what are the possible dimensions of the photo according to his notes. As there are multiple possible answers, find the dimensions with the minimal possible area of the rectangle.",['math']507"The spring is coming and it means that a lot of fruits appear on the counters. One sunny day little boy Valera decided to go shopping. He made a list of m fruits he wanted to buy. If Valera want to buy more than one fruit of some kind, he includes it into the list several times. When he came to the fruit stall of Ashot, he saw that the seller hadn't distributed price tags to the goods, but put all price tags on the counter. Later Ashot will attach every price tag to some kind of fruits, and Valera will be able to count the total price of all fruits from his list. But Valera wants to know now what can be the smallest total price (in case of the most «lucky» for him distribution of price tags) and the largest total price (in case of the most «unlucky» for him distribution of price tags).",[]508"You are given a string $$$s$$$ consisting of $$$n$$$ lowercase Latin letters. $$$n$$$ is even.For each position $$$i$$$ ($$$1 \le i \le n$$$) in string $$$s$$$ you are required to change the letter on this position either to the previous letter in alphabetic order or to the next one (letters 'a' and 'z' have only one of these options). Letter in every position must be changed exactly once.For example, letter 'p' should be changed either to 'o' or to 'q', letter 'a' should be changed to 'b' and letter 'z' should be changed to 'y'.That way string ""codeforces"", for example, can be changed to ""dpedepqbft"" ('c' $$$\rightarrow$$$ 'd', 'o' $$$\rightarrow$$$ 'p', 'd' $$$\rightarrow$$$ 'e', 'e' $$$\rightarrow$$$ 'd', 'f' $$$\rightarrow$$$ 'e', 'o' $$$\rightarrow$$$ 'p', 'r' $$$\rightarrow$$$ 'q', 'c' $$$\rightarrow$$$ 'b', 'e' $$$\rightarrow$$$ 'f', 's' $$$\rightarrow$$$ 't').String $$$s$$$ is called a palindrome if it reads the same from left to right and from right to left. For example, strings ""abba"" and ""zz"" are palindromes and strings ""abca"" and ""zy"" are not.Your goal is to check if it's possible to make string $$$s$$$ a palindrome by applying the aforementioned changes to every position. Print ""YES"" if string $$$s$$$ can be transformed to a palindrome and ""NO"" otherwise.Each testcase contains several strings, for each of them you are required to solve the problem separately.",['strings']509"This is an interactive problem!In the last regional contest Hemose, ZeyadKhattab and YahiaSherif — members of the team Carpe Diem — did not qualify to ICPC because of some unknown reasons. Hemose was very sad and had a bad day after the contest, but ZeyadKhattab is very wise and knows Hemose very well, and does not want to see him sad.Zeyad knows that Hemose loves tree problems, so he gave him a tree problem with a very special device.Hemose has a weighted tree with $$$n$$$ nodes and $$$n-1$$$ edges. Unfortunately, Hemose doesn't remember the weights of edges.Let's define $$$Dist(u, v)$$$ for $$$u\neq v$$$ as the greatest common divisor of the weights of all edges on the path from node $$$u$$$ to node $$$v$$$.Hemose has a special device. Hemose can give the device a set of nodes, and the device will return the largest $$$Dist$$$ between any two nodes from the set. More formally, if Hemose gives the device a set $$$S$$$ of nodes, the device will return the largest value of $$$Dist(u, v)$$$ over all pairs $$$(u, v)$$$ with $$$u$$$, $$$v$$$ $$$\in$$$ $$$S$$$ and $$$u \neq v$$$.Hemose can use this Device at most $$$12$$$ times, and wants to find any two distinct nodes $$$a$$$, $$$b$$$, such that $$$Dist(a, b)$$$ is maximum possible. Can you help him?","['math', 'number theory', 'trees']"510"You are given an array of $$$n$$$ positive integers $$$a_1, a_2, \ldots, a_n$$$. Your task is to calculate the number of arrays of $$$n$$$ positive integers $$$b_1, b_2, \ldots, b_n$$$ such that:   $$$1 \le b_i \le a_i$$$ for every $$$i$$$ ($$$1 \le i \le n$$$), and  $$$b_i \neq b_{i+1}$$$ for every $$$i$$$ ($$$1 \le i \le n - 1$$$). The number of such arrays can be very large, so print it modulo $$$998\,244\,353$$$.",['math']511"This is an interactive problem.Farmer Stanley grows corn on a rectangular field of size $$$ n \times m $$$ meters with corners in points $$$(0, 0)$$$, $$$(0, m)$$$, $$$(n, 0)$$$, $$$(n, m)$$$. This year the harvest was plentiful and corn covered the whole field.The night before harvest aliens arrived and poisoned the corn in a single $$$1 \times 1$$$ square with sides parallel to field borders. The corn inside the square must not be eaten, but you cannot distinguish it from ordinary corn by sight. Stanley can only collect a sample of corn from an arbitrary polygon and bring it to the laboratory, where it will be analyzed and Stanley will be told the amount of corn in the sample that was poisoned. Since the harvest will soon deteriorate, such a study can be carried out no more than $$$5$$$ times.More formally, it is allowed to make no more than $$$5$$$ queries, each of them calculates the area of intersection of a chosen polygon with a square of poisoned corn. It is necessary to find out the coordinates of the lower-left corner of the drawn square (the vertex of the square with the smallest $$$x$$$ and $$$y$$$ coordinates).","['math', 'geometry']"512"You are given array $$$a_1, a_2, \dots, a_n$$$. Find the subsegment $$$a_l, a_{l+1}, \dots, a_r$$$ ($$$1 \le l \le r \le n$$$) with maximum arithmetic mean $$$\frac{1}{r - l + 1}\sum\limits_{i=l}^{r}{a_i}$$$ (in floating-point numbers, i.e. without any rounding).If there are many such subsegments find the longest one.",['math']513"A camera you have accidentally left in a desert has taken an interesting photo. The photo has a resolution of n pixels width, and each column of this photo is all white or all black. Thus, we can represent the photo as a sequence of n zeros and ones, where 0 means that the corresponding column is all white, and 1 means that the corresponding column is black.You think that this photo can contain a zebra. In this case the whole photo should consist of several (possibly, only one) alternating black and white stripes of equal width. For example, the photo [0, 0, 0, 1, 1, 1, 0, 0, 0] can be a photo of zebra, while the photo [0, 0, 0, 1, 1, 1, 1] can not, because the width of the black stripe is 3, while the width of the white stripe is 4. Can the given photo be a photo of zebra or not?",[]514"You are given an array $$$a$$$ consisting of $$$n$$$ positive integers. You have to choose a positive integer $$$d$$$ and paint all elements into two colors. All elements which are divisible by $$$d$$$ will be painted red, and all other elements will be painted blue.The coloring is called beautiful if there are no pairs of adjacent elements with the same color in the array. Your task is to find any value of $$$d$$$ which yields a beautiful coloring, or report that it is impossible.",['math']515"Valera's finally decided to go on holiday! He packed up and headed for a ski resort.Valera's fancied a ski trip but he soon realized that he could get lost in this new place. Somebody gave him a useful hint: the resort has n objects (we will consider the objects indexed in some way by integers from 1 to n), each object is either a hotel or a mountain.Valera has also found out that the ski resort had multiple ski tracks. Specifically, for each object v, the resort has at most one object u, such that there is a ski track built from object u to object v. We also know that no hotel has got a ski track leading from the hotel to some object.Valera is afraid of getting lost on the resort. So he wants you to come up with a path he would walk along. The path must consist of objects v1, v2, ..., vk (k ≥ 1) and meet the following conditions:  Objects with numbers v1, v2, ..., vk - 1 are mountains and the object with number vk is the hotel.  For any integer i (1 ≤ i < k), there is exactly one ski track leading from object vi. This track goes to object vi + 1.  The path contains as many objects as possible (k is maximal). Help Valera. Find such path that meets all the criteria of our hero!",['graphs']516"You are given a chessboard of size $$$n \times n$$$. It is filled with numbers from $$$1$$$ to $$$n^2$$$ in the following way: the first $$$\lceil \frac{n^2}{2} \rceil$$$ numbers from $$$1$$$ to $$$\lceil \frac{n^2}{2} \rceil$$$ are written in the cells with even sum of coordinates from left to right from top to bottom. The rest $$$n^2 - \lceil \frac{n^2}{2} \rceil$$$ numbers from $$$\lceil \frac{n^2}{2} \rceil + 1$$$ to $$$n^2$$$ are written in the cells with odd sum of coordinates from left to right from top to bottom. The operation $$$\lceil\frac{x}{y}\rceil$$$ means division $$$x$$$ by $$$y$$$ rounded up.For example, the left board on the following picture is the chessboard which is given for $$$n=4$$$ and the right board is the chessboard which is given for $$$n=5$$$.  You are given $$$q$$$ queries. The $$$i$$$-th query is described as a pair $$$x_i, y_i$$$. The answer to the $$$i$$$-th query is the number written in the cell $$$x_i, y_i$$$ ($$$x_i$$$ is the row, $$$y_i$$$ is the column). Rows and columns are numbered from $$$1$$$ to $$$n$$$.",['math']517"Tom loves vowels, and he likes long words with many vowels. His favorite words are vowelly words. We say a word of length $$$k$$$ is vowelly if there are positive integers $$$n$$$ and $$$m$$$ such that $$$n\cdot m = k$$$ and when the word is written by using $$$n$$$ rows and $$$m$$$ columns (the first row is filled first, then the second and so on, with each row filled from left to right), every vowel of the English alphabet appears at least once in every row and every column.You are given an integer $$$k$$$ and you must either print a vowelly word of length $$$k$$$ or print $$$-1$$$ if no such word exists.In this problem the vowels of the English alphabet are 'a', 'e', 'i', 'o' ,'u'.","['math', 'number theory']"518"You have a simple and connected undirected graph consisting of $$$n$$$ nodes and $$$m$$$ edges.Consider any way to pair some subset of these $$$n$$$ nodes such that no node is present in more than one pair. This pairing is valid if for every pair of pairs, the induced subgraph containing all $$$4$$$ nodes, two from each pair, has at most $$$2$$$ edges (out of the $$$6$$$ possible edges). More formally, for any two pairs, $$$(a,b)$$$ and $$$(c,d)$$$, the induced subgraph with nodes $$$\{a,b,c,d\}$$$ should have at most $$$2$$$ edges. Please note that the subgraph induced by a set of nodes contains nodes only from this set and edges which have both of its end points in this set.Now, do one of the following:   Find a simple path consisting of at least $$$\lceil \frac{n}{2} \rceil$$$ nodes. Here, a path is called simple if it does not visit any node multiple times.  Find a valid pairing in which at least $$$\lceil \frac{n}{2} \rceil$$$ nodes are paired. It can be shown that it is possible to find at least one of the two in every graph satisfying constraints from the statement. ","['graphs', 'trees']"519"In the evenings Donkey would join Shrek to look at the stars. They would sit on a log, sipping tea and they would watch the starry sky. The sky hung above the roof, right behind the chimney. Shrek's stars were to the right of the chimney and the Donkey's stars were to the left. Most days the Donkey would just count the stars, so he knew that they are exactly n. This time he wanted a challenge. He imagined a coordinate system: he put the origin of the coordinates at the intersection of the roof and the chimney, directed the OX axis to the left along the roof and the OY axis — up along the chimney (see figure). The Donkey imagined two rays emanating from he origin of axes at angles α1 and α2 to the OX axis.  Now he chooses any star that lies strictly between these rays. After that he imagines more rays that emanate from this star at the same angles α1 and α2 to the OX axis and chooses another star that lies strictly between the new rays. He repeats the operation as long as there still are stars he can choose between the rays that emanate from a star.   As a result, the Donkey gets a chain of stars. He can consecutively get to each star if he acts by the given rules.Your task is to find the maximum number of stars m that the Donkey's chain can contain.Note that the chain must necessarily start in the point of the origin of the axes, that isn't taken into consideration while counting the number m of stars in the chain.","['math', 'geometry']"520"There is a grid, consisting of $$$n$$$ rows and $$$m$$$ columns. Each cell of the grid is either free or blocked. One of the free cells contains a lab. All the cells beyond the borders of the grid are also blocked.A crazy robot has escaped from this lab. It is currently in some free cell of the grid. You can send one of the following commands to the robot: ""move right"", ""move down"", ""move left"" or ""move up"". Each command means moving to a neighbouring cell in the corresponding direction.However, as the robot is crazy, it will do anything except following the command. Upon receiving a command, it will choose a direction such that it differs from the one in command and the cell in that direction is not blocked. If there is such a direction, then it will move to a neighbouring cell in that direction. Otherwise, it will do nothing.We want to get the robot to the lab to get it fixed. For each free cell, determine if the robot can be forced to reach the lab starting in this cell. That is, after each step of the robot a command can be sent to a robot such that no matter what different directions the robot chooses, it will end up in a lab.",['graphs']521"The New Year is coming! That's why many people today are busy preparing New Year presents. Vasily the Programmer is no exception.Vasily knows that the best present is (no, it's not a contest) money. He's put n empty wallets from left to right in a row and decided how much money to put in what wallet. Vasily decided to put ai coins to the i-th wallet from the left.Vasily is a very busy man, so the money are sorted into the bags by his robot. Initially, the robot stands by the leftmost wallet in the row. The robot can follow instructions of three types: go to the wallet that is to the left of the current one (if such wallet exists), go to the wallet that is to the right of the current one (if such wallet exists), put a coin to the current wallet. Due to some technical malfunctions the robot cannot follow two ""put a coin"" instructions in a row.Vasily doesn't want to wait for long, so he wants to write a program for the robot that contains at most 106 operations (not necessarily minimum in length) the robot can use to put coins into the wallets. Help him.",[]522"Alex decided to go on a touristic trip over the country.For simplicity let's assume that the country has $$$n$$$ cities and $$$m$$$ bidirectional roads connecting them. Alex lives in city $$$s$$$ and initially located in it. To compare different cities Alex assigned each city a score $$$w_i$$$ which is as high as interesting city seems to Alex.Alex believes that his trip will be interesting only if he will not use any road twice in a row. That is if Alex came to city $$$v$$$ from city $$$u$$$, he may choose as the next city in the trip any city connected with $$$v$$$ by the road, except for the city $$$u$$$.Your task is to help Alex plan his city in a way that maximizes total score over all cities he visited. Note that for each city its score is counted at most once, even if Alex been there several times during his trip.","['graphs', 'trees']"523"  One morning the Cereal Guy found out that all his cereal flakes were gone. He found a note instead of them. It turned out that his smart roommate hid the flakes in one of n boxes. The boxes stand in one row, they are numbered from 1 to n from the left to the right. The roommate left hints like ""Hidden to the left of the i-th box"" (""To the left of i""), ""Hidden to the right of the i-th box"" (""To the right of i""). Such hints mean that there are no flakes in the i-th box as well. The Cereal Guy wants to know the minimal number of boxes he necessarily needs to check to find the flakes considering all the hints. Or he wants to find out that the hints are contradictory and the roommate lied to him, that is, no box has the flakes.",[]524"Nauuo is a girl who loves playing chess.One day she invented a game by herself which needs $$$n$$$ chess pieces to play on a $$$m\times m$$$ chessboard. The rows and columns are numbered from $$$1$$$ to $$$m$$$. We denote a cell on the intersection of the $$$r$$$-th row and $$$c$$$-th column as $$$(r,c)$$$.The game's goal is to place $$$n$$$ chess pieces numbered from $$$1$$$ to $$$n$$$ on the chessboard, the $$$i$$$-th piece lies on $$$(r_i,\,c_i)$$$, while the following rule is satisfied: for all pairs of pieces $$$i$$$ and $$$j$$$, $$$|r_i-r_j|+|c_i-c_j|\ge|i-j|$$$. Here $$$|x|$$$ means the absolute value of $$$x$$$.However, Nauuo discovered that sometimes she couldn't find a solution because the chessboard was too small.She wants to find the smallest chessboard on which she can put $$$n$$$ pieces according to the rules.She also wonders how to place the pieces on such a chessboard. Can you help her?",[]525"Allen wants to enter a fan zone that occupies a round square and has $$$n$$$ entrances.There already is a queue of $$$a_i$$$ people in front of the $$$i$$$-th entrance. Each entrance allows one person from its queue to enter the fan zone in one minute.Allen uses the following strategy to enter the fan zone:   Initially he stands in the end of the queue in front of the first entrance.  Each minute, if he is not allowed into the fan zone during the minute (meaning he is not the first in the queue), he leaves the current queue and stands in the end of the queue of the next entrance (or the first entrance if he leaves the last entrance). Determine the entrance through which Allen will finally enter the fan zone.",['math']526"The legendary Farmer John is throwing a huge party, and animals from all over the world are hanging out at his house. His guests are hungry, so he instructs his cow Bessie to bring out the snacks! Moo!There are $$$n$$$ snacks flavors, numbered with integers $$$1, 2, \ldots, n$$$. Bessie has $$$n$$$ snacks, one snack of each flavor. Every guest has exactly two favorite flavors. The procedure for eating snacks will go as follows:  First, Bessie will line up the guests in some way.  Then in this order, guests will approach the snacks one by one.  Each guest in their turn will eat all remaining snacks of their favorite flavor. In case no favorite flavors are present when a guest goes up, they become very sad.  Help Bessie to minimize the number of sad guests by lining the guests in an optimal way.",['graphs']527"There are n knights sitting at the Round Table at an equal distance from each other. Each of them is either in a good or in a bad mood.Merlin, the wizard predicted to King Arthur that the next month will turn out to be particularly fortunate if the regular polygon can be found. On all vertices of the polygon knights in a good mood should be located. Otherwise, the next month will bring misfortunes.A convex polygon is regular if all its sides have same length and all his angles are equal. In this problem we consider only regular polygons with at least 3 vertices, i. e. only nondegenerated.On a picture below some examples of such polygons are present. Green points mean knights in a good mood. Red points mean ones in a bad mood.  King Arthur knows the knights' moods. Help him find out if the next month will be fortunate or not.","['math', 'number theory']"528"There is an array $$$a$$$ of length $$$n$$$. You may perform the following operation any number of times:  Choose two indices $$$l$$$ and $$$r$$$ where $$$1 \le l < r \le n$$$ and $$$a_l = a_r$$$. Then, set $$$a[l \ldots r] = [a_{l+1}, a_{l+2}, \ldots, a_r, a_l]$$$. You are also given another array $$$b$$$ of length $$$n$$$ which is a permutation of $$$a$$$. Determine whether it is possible to transform array $$$a$$$ into an array $$$b$$$ using the above operation some number of times.",[]529"A bracket sequence is a string containing only characters ""("" and "")"".A regular bracket sequence is a bracket sequence that can be transformed into a correct arithmetic expression by inserting characters ""1"" and ""+"" between the original characters of the sequence. For example, bracket sequences ""()()"", ""(())"" are regular (the resulting expressions are: ""(1)+(1)"", ""((1+1)+1)""), and "")("" and ""("" are not.You are given $$$n$$$ bracket sequences $$$s_1, s_2, \dots , s_n$$$. Calculate the number of pairs $$$i, j \, (1 \le i, j \le n)$$$ such that the bracket sequence $$$s_i + s_j$$$ is a regular bracket sequence. Operation $$$+$$$ means concatenation i.e. ""()("" + "")()"" = ""()()()"".If $$$s_i + s_j$$$ and $$$s_j + s_i$$$ are regular bracket sequences and $$$i \ne j$$$, then both pairs $$$(i, j)$$$ and $$$(j, i)$$$ must be counted in the answer. Also, if $$$s_i + s_i$$$ is a regular bracket sequence, the pair $$$(i, i)$$$ must be counted in the answer.",[]530"New Year is coming in Tree World! In this world, as the name implies, there are n cities connected by n - 1 roads, and for any two distinct cities there always exists a path between them. The cities are numbered by integers from 1 to n, and the roads are numbered by integers from 1 to n - 1. Let's define d(u, v) as total length of roads on the path between city u and city v.As an annual event, people in Tree World repairs exactly one road per year. As a result, the length of one road decreases. It is already known that in the i-th year, the length of the ri-th road is going to become wi, which is shorter than its length before. Assume that the current year is year 1.Three Santas are planning to give presents annually to all the children in Tree World. In order to do that, they need some preparation, so they are going to choose three distinct cities c1, c2, c3 and make exactly one warehouse in each city. The k-th (1 ≤ k ≤ 3) Santa will take charge of the warehouse in city ck.It is really boring for the three Santas to keep a warehouse alone. So, they decided to build an only-for-Santa network! The cost needed to build this network equals to d(c1, c2) + d(c2, c3) + d(c3, c1) dollars. Santas are too busy to find the best place, so they decided to choose c1, c2, c3 randomly uniformly over all triples of distinct numbers from 1 to n. Santas would like to know the expected value of the cost needed to build the network.However, as mentioned, each year, the length of exactly one road decreases. So, the Santas want to calculate the expected after each length change. Help them to calculate the value.","['graphs', 'trees']"531"Polycarp was gifted an array $$$a$$$ of length $$$n$$$. Polycarp considers an array beautiful if there exists a number $$$C$$$, such that each number in the array occurs either zero or $$$C$$$ times. Polycarp wants to remove some elements from the array $$$a$$$ to make it beautiful.For example, if $$$n=6$$$ and $$$a = [1, 3, 2, 1, 4, 2]$$$, then the following options are possible to make the array $$$a$$$ array beautiful:   Polycarp removes elements at positions $$$2$$$ and $$$5$$$, array $$$a$$$ becomes equal to $$$[1, 2, 1, 2]$$$;  Polycarp removes elements at positions $$$1$$$ and $$$6$$$, array $$$a$$$ becomes equal to $$$[3, 2, 1, 4]$$$;  Polycarp removes elements at positions $$$1, 2$$$ and $$$6$$$, array $$$a$$$ becomes equal to $$$[2, 1, 4]$$$; Help Polycarp determine the minimum number of elements to remove from the array $$$a$$$ to make it beautiful.",['math']532"Vanya walks late at night along a straight street of length l, lit by n lanterns. Consider the coordinate system with the beginning of the street corresponding to the point 0, and its end corresponding to the point l. Then the i-th lantern is at the point ai. The lantern lights all points of the street that are at the distance of at most d from it, where d is some positive number, common for all lanterns. Vanya wonders: what is the minimum light radius d should the lanterns have to light the whole street?",['math']533"Ivan has $$$n$$$ songs on his phone. The size of the $$$i$$$-th song is $$$a_i$$$ bytes. Ivan also has a flash drive which can hold at most $$$m$$$ bytes in total. Initially, his flash drive is empty.Ivan wants to copy all $$$n$$$ songs to the flash drive. He can compress the songs. If he compresses the $$$i$$$-th song, the size of the $$$i$$$-th song reduces from $$$a_i$$$ to $$$b_i$$$ bytes ($$$b_i < a_i$$$).Ivan can compress any subset of the songs (possibly empty) and copy all the songs to his flash drive if the sum of their sizes is at most $$$m$$$. He can compress any subset of the songs (not necessarily contiguous).Ivan wants to find the minimum number of songs he needs to compress in such a way that all his songs fit on the drive (i.e. the sum of their sizes is less than or equal to $$$m$$$).If it is impossible to copy all the songs (even if Ivan compresses all the songs), print ""-1"". Otherwise print the minimum number of songs Ivan needs to compress.",[]534"Suppose you have a special $$$x$$$-$$$y$$$-counter. This counter can store some value as a decimal number; at first, the counter has value $$$0$$$. The counter performs the following algorithm: it prints its lowest digit and, after that, adds either $$$x$$$ or $$$y$$$ to its value. So all sequences this counter generates are starting from $$$0$$$. For example, a $$$4$$$-$$$2$$$-counter can act as follows:  it prints $$$0$$$, and adds $$$4$$$ to its value, so the current value is $$$4$$$, and the output is $$$0$$$;  it prints $$$4$$$, and adds $$$4$$$ to its value, so the current value is $$$8$$$, and the output is $$$04$$$;  it prints $$$8$$$, and adds $$$4$$$ to its value, so the current value is $$$12$$$, and the output is $$$048$$$;  it prints $$$2$$$, and adds $$$2$$$ to its value, so the current value is $$$14$$$, and the output is $$$0482$$$;  it prints $$$4$$$, and adds $$$4$$$ to its value, so the current value is $$$18$$$, and the output is $$$04824$$$. This is only one of the possible outputs; for example, the same counter could generate $$$0246802468024$$$ as the output, if we chose to add $$$2$$$ during each step.You wrote down a printed sequence from one of such $$$x$$$-$$$y$$$-counters. But the sequence was corrupted and several elements from the sequence could be erased.Now you'd like to recover data you've lost, but you don't even know the type of the counter you used. You have a decimal string $$$s$$$ — the remaining data of the sequence. For all $$$0 \le x, y < 10$$$, calculate the minimum number of digits you have to insert in the string $$$s$$$ to make it a possible output of the $$$x$$$-$$$y$$$-counter. Note that you can't change the order of digits in string $$$s$$$ or erase any of them; only insertions are allowed.",[]535"Local authorities have heard a lot about combinatorial abilities of Ostap Bender so they decided to ask his help in the question of urbanization. There are n people who plan to move to the cities. The wealth of the i of them is equal to ai. Authorities plan to build two cities, first for n1 people and second for n2 people. Of course, each of n candidates can settle in only one of the cities. Thus, first some subset of candidates of size n1 settle in the first city and then some subset of size n2 is chosen among the remaining candidates and the move to the second city. All other candidates receive an official refuse and go back home.To make the statistic of local region look better in the eyes of their bosses, local authorities decided to pick subsets of candidates in such a way that the sum of arithmetic mean of wealth of people in each of the cities is as large as possible. Arithmetic mean of wealth in one city is the sum of wealth ai among all its residents divided by the number of them (n1 or n2 depending on the city). The division should be done in real numbers without any rounding.Please, help authorities find the optimal way to pick residents for two cities.",['number theory']536"This is the easy version of the problem. The only difference is that in this version $$$k = 0$$$.There is an array $$$a_1, a_2, \ldots, a_n$$$ of $$$n$$$ positive integers. You should divide it into a minimal number of continuous segments, such that in each segment there are no two numbers (on different positions), whose product is a perfect square.Moreover, it is allowed to do at most $$$k$$$ such operations before the division: choose a number in the array and change its value to any positive integer. But in this version $$$k = 0$$$, so it is not important.What is the minimum number of continuous segments you should use if you will make changes optimally?","['math', 'number theory']"537"Inna is a great piano player and Dima is a modest guitar player. Dima has recently written a song and they want to play it together. Of course, Sereja wants to listen to the song very much. A song is a sequence of notes. Dima and Inna want to play each note at the same time. At that, they can play the i-th note at volume v (1 ≤ v ≤ ai; v is an integer) both on the piano and the guitar. They should retain harmony, so the total volume with which the i-th note was played on the guitar and the piano must equal bi. If Dima and Inna cannot play a note by the described rules, they skip it and Sereja's joy drops by 1. But if Inna and Dima play the i-th note at volumes xi and yi (xi + yi = bi) correspondingly, Sereja's joy rises by xi·yi. Sereja has just returned home from the university and his current joy is 0. Help Dima and Inna play the song so as to maximize Sereja's total joy after listening to the whole song!",[]538Vasya decided to write an anonymous letter cutting the letters out of a newspaper heading. He knows heading s1 and text s2 that he wants to send. Vasya can use every single heading letter no more than once. Vasya doesn't have to cut the spaces out of the heading — he just leaves some blank space to mark them. Help him; find out if he will manage to compose the needed text.,['strings']539"You are given a tube which is reflective inside represented as two non-coinciding, but parallel to $$$Ox$$$ lines. Each line has some special integer points — positions of sensors on sides of the tube.You are going to emit a laser ray in the tube. To do so, you have to choose two integer points $$$A$$$ and $$$B$$$ on the first and the second line respectively (coordinates can be negative): the point $$$A$$$ is responsible for the position of the laser, and the point $$$B$$$ — for the direction of the laser ray. The laser ray is a ray starting at $$$A$$$ and directed at $$$B$$$ which will reflect from the sides of the tube (it doesn't matter if there are any sensors at a reflection point or not). A sensor will only register the ray if the ray hits exactly at the position of the sensor.   Examples of laser rays. Note that image contains two examples. The $$$3$$$ sensors (denoted by black bold points on the tube sides) will register the blue ray but only $$$2$$$ will register the red. Calculate the maximum number of sensors which can register your ray if you choose points $$$A$$$ and $$$B$$$ on the first and the second lines respectively.",['math']540Convexity of a set of points on the plane is the size of the largest subset of points that form a convex polygon. Your task is to build a set of n points with the convexity of exactly m. Your set of points should not contain three points that lie on a straight line.,['geometry']541"Little penguin Polo adores integer segments, that is, pairs of integers [l; r] (l ≤ r). He has a set that consists of n integer segments: [l1; r1], [l2; r2], ..., [ln; rn]. We know that no two segments of this set intersect. In one move Polo can either widen any segment of the set 1 unit to the left or 1 unit to the right, that is transform [l; r] to either segment [l - 1; r], or to segment [l; r + 1].The value of a set of segments that consists of n segments [l1; r1], [l2; r2], ..., [ln; rn] is the number of integers x, such that there is integer j, for which the following inequality holds, lj ≤ x ≤ rj.Find the minimum number of moves needed to make the value of the set of Polo's segments divisible by k.",[]542"Farmer John has just given the cows a program to play with! The program contains two integer variables, x and y, and performs the following operations on a sequence a1, a2, ..., an of positive integers:  Initially, x = 1 and y = 0. If, after any step, x ≤ 0 or x > n, the program immediately terminates.  The program increases both x and y by a value equal to ax simultaneously.  The program now increases y by ax while decreasing x by ax.  The program executes steps 2 and 3 (first step 2, then step 3) repeatedly until it terminates (it may never terminate). So, the sequence of executed steps may start with: step 2, step 3, step 2, step 3, step 2 and so on. The cows are not very good at arithmetic though, and they want to see how the program works. Please help them!You are given the sequence a2, a3, ..., an. Suppose for each i (1 ≤ i ≤ n - 1) we run the program on the sequence i, a2, a3, ..., an. For each such run output the final value of y if the program terminates or -1 if it does not terminate.",[]543"Fox Ciel is playing a game. In this game there is an infinite long tape with cells indexed by integers (positive, negative and zero). At the beginning she is standing at the cell 0.There are also n cards, each card has 2 attributes: length li and cost ci. If she pays ci dollars then she can apply i-th card. After applying i-th card she becomes able to make jumps of length li, i. e. from cell x to cell (x - li) or cell (x + li).She wants to be able to jump to any cell on the tape (possibly, visiting some intermediate cells). For achieving this goal, she wants to buy some cards, paying as little money as possible. If this is possible, calculate the minimal cost.","['math', 'number theory']"544"Eugeny loves listening to music. He has n songs in his play list. We know that song number i has the duration of ti minutes. Eugeny listens to each song, perhaps more than once. He listens to song number i ci times. Eugeny's play list is organized as follows: first song number 1 plays c1 times, then song number 2 plays c2 times, ..., in the end the song number n plays cn times.Eugeny took a piece of paper and wrote out m moments of time when he liked a song. Now for each such moment he wants to know the number of the song that played at that moment. The moment x means that Eugeny wants to know which song was playing during the x-th minute of his listening to the play list.Help Eugeny and calculate the required numbers of songs.",[]545"Polycarpus has n markers and m marker caps. Each marker is described by two numbers: xi is the color and yi is the diameter. Correspondingly, each cap is described by two numbers: aj is the color and bj is the diameter. Cap (aj, bj) can close marker (xi, yi) only if their diameters match, that is, bj = yi. Besides, a marker is considered to be beautifully closed, if the cap color and the marker color match, that is, aj = xi.Find the way to close the maximum number of markers. If there are several such ways, then choose the one that has the maximum number of beautifully closed markers.",[]546"Authors have come up with the string $$$s$$$ consisting of $$$n$$$ lowercase Latin letters.You are given two permutations of its indices (not necessary equal) $$$p$$$ and $$$q$$$ (both of length $$$n$$$). Recall that the permutation is the array of length $$$n$$$ which contains each integer from $$$1$$$ to $$$n$$$ exactly once.For all $$$i$$$ from $$$1$$$ to $$$n-1$$$ the following properties hold: $$$s[p_i] \le s[p_{i + 1}]$$$ and $$$s[q_i] \le s[q_{i + 1}]$$$. It means that if you will write down all characters of $$$s$$$ in order of permutation indices, the resulting string will be sorted in the non-decreasing order.Your task is to restore any such string $$$s$$$ of length $$$n$$$ consisting of at least $$$k$$$ distinct lowercase Latin letters which suits the given permutations.If there are multiple answers, you can print any of them.","['graphs', 'strings']"547"This problem is interactive.We have hidden an array $$$a$$$ of $$$n$$$ pairwise different numbers (this means that no two numbers are equal). You can get some information about this array using a new device you just ordered on Amazon. This device can answer queries of the following form: in response to the positions of $$$k$$$ different elements of the array, it will return the position and value of the $$$m$$$-th among them in the ascending order.Unfortunately, the instruction for the device was lost during delivery. However, you remember $$$k$$$, but don't remember $$$m$$$. Your task is to find $$$m$$$ using queries to this device. You can ask not more than $$$n$$$ queries.Note that the array $$$a$$$ and number $$$m$$$ are fixed before the start of the interaction and don't depend on your queries. In other words, interactor is not adaptive.Note that you don't have to minimize the number of queries, and you don't need to guess array $$$a$$$. You just have to guess $$$m$$$.",['math']548"One day, ZS the Coder wrote down an array of integers a with elements a1,  a2,  ...,  an.A subarray of the array a is a sequence al,  al  +  1,  ...,  ar for some integers (l,  r) such that 1  ≤  l  ≤  r  ≤  n. ZS the Coder thinks that a subarray of a is beautiful if the bitwise xor of all the elements in the subarray is at least k.Help ZS the Coder find the number of beautiful subarrays of a!","['strings', 'trees']"549"You are given a binary array$$$^{\dagger}$$$ of length $$$n$$$. You are allowed to perform one operation on it at most once. In an operation, you can choose any element and flip it: turn a $$$0$$$ into a $$$1$$$ or vice-versa.What is the maximum number of inversions$$$^{\ddagger}$$$ the array can have after performing at most one operation?$$$^\dagger$$$ A binary array is an array that contains only zeroes and ones.$$$^\ddagger$$$ The number of inversions in an array is the number of pairs of indices $$$i,j$$$ such that $$$i<j$$$ and $$$a_i > a_j$$$.",['math']550"Not so long ago, Vlad came up with an interesting function: $$$f_a(x)=\left\lfloor\frac{x}{a}\right\rfloor + x \bmod a$$$, where $$$\left\lfloor\frac{x}{a}\right\rfloor$$$ is $$$\frac{x}{a}$$$, rounded down, $$$x \bmod a$$$ — the remainder of the integer division of $$$x$$$ by $$$a$$$.For example, with $$$a=3$$$ and $$$x=11$$$, the value $$$f_3(11) = \left\lfloor\frac{11}{3}\right\rfloor + 11 \bmod 3 = 3 + 2 = 5$$$.The number $$$a$$$ is fixed and known to Vlad. Help Vlad find the maximum value of $$$f_a(x)$$$ if $$$x$$$ can take any integer value from $$$l$$$ to $$$r$$$ inclusive ($$$l \le x \le r$$$).",['math']551"There are $$$n$$$ robbers at coordinates $$$(a_1, b_1)$$$, $$$(a_2, b_2)$$$, ..., $$$(a_n, b_n)$$$ and $$$m$$$ searchlight at coordinates $$$(c_1, d_1)$$$, $$$(c_2, d_2)$$$, ..., $$$(c_m, d_m)$$$. In one move you can move each robber to the right (increase $$$a_i$$$ of each robber by one) or move each robber up (increase $$$b_i$$$ of each robber by one). Note that you should either increase all $$$a_i$$$ or all $$$b_i$$$, you can't increase $$$a_i$$$ for some points and $$$b_i$$$ for some other points.Searchlight $$$j$$$ can see a robber $$$i$$$ if $$$a_i \leq c_j$$$ and $$$b_i \leq d_j$$$. A configuration of robbers is safe if no searchlight can see a robber (i.e. if there is no pair $$$i,j$$$ such that searchlight $$$j$$$ can see a robber $$$i$$$).What is the minimum number of moves you need to perform to reach a safe configuration?",[]552"You are given $$$n$$$ pairs of integers $$$(a_1, b_1), (a_2, b_2), \ldots, (a_n, b_n)$$$. All of the integers in the pairs are distinct and are in the range from $$$1$$$ to $$$2 \cdot n$$$ inclusive.Let's call a sequence of integers $$$x_1, x_2, \ldots, x_{2k}$$$ good if either   $$$x_1 < x_2 > x_3 < \ldots < x_{2k-2} > x_{2k-1} < x_{2k}$$$, or  $$$x_1 > x_2 < x_3 > \ldots > x_{2k-2} < x_{2k-1} > x_{2k}$$$. You need to choose a subset of distinct indices $$$i_1, i_2, \ldots, i_t$$$ and their order in a way that if you write down all numbers from the pairs in a single sequence (the sequence would be $$$a_{i_1}, b_{i_1}, a_{i_2}, b_{i_2}, \ldots, a_{i_t}, b_{i_t}$$$), this sequence is good.What is the largest subset of indices you can choose? You also need to construct the corresponding index sequence $$$i_1, i_2, \ldots, i_t$$$.",[]553"You are given a sequence of integers of length $$$n$$$ and integer number $$$k$$$. You should print any integer number $$$x$$$ in the range of $$$[1; 10^9]$$$ (i.e. $$$1 \le x \le 10^9$$$) such that exactly $$$k$$$ elements of given sequence are less than or equal to $$$x$$$.Note that the sequence can contain equal elements.If there is no such $$$x$$$, print ""-1"" (without quotes).",[]554"The only difference between easy and hard versions is the length of the string. You can hack this problem only if you solve both problems.Kirk has a binary string $$$s$$$ (a string which consists of zeroes and ones) of length $$$n$$$ and he is asking you to find a binary string $$$t$$$ of the same length which satisfies the following conditions: For any $$$l$$$ and $$$r$$$ ($$$1 \leq l \leq r \leq n$$$) the length of the longest non-decreasing subsequence of the substring $$$s_{l}s_{l+1} \ldots s_{r}$$$ is equal to the length of the longest non-decreasing subsequence of the substring $$$t_{l}t_{l+1} \ldots t_{r}$$$; The number of zeroes in $$$t$$$ is the maximum possible.A non-decreasing subsequence of a string $$$p$$$ is a sequence of indices $$$i_1, i_2, \ldots, i_k$$$ such that $$$i_1 < i_2 < \ldots < i_k$$$ and $$$p_{i_1} \leq p_{i_2} \leq \ldots \leq p_{i_k}$$$. The length of the subsequence is $$$k$$$.If there are multiple substrings which satisfy the conditions, output any.",['strings']555"You are given a ternary string (it is a string which consists only of characters '0', '1' and '2').You can swap any two adjacent (consecutive) characters '0' and '1' (i.e. replace ""01"" with ""10"" or vice versa) or any two adjacent (consecutive) characters '1' and '2' (i.e. replace ""12"" with ""21"" or vice versa).For example, for string ""010210"" we can perform the following moves:   ""010210"" $$$\rightarrow$$$ ""100210"";  ""010210"" $$$\rightarrow$$$ ""001210"";  ""010210"" $$$\rightarrow$$$ ""010120"";  ""010210"" $$$\rightarrow$$$ ""010201"". Note than you cannot swap ""02"" $$$\rightarrow$$$ ""20"" and vice versa. You cannot perform any other operations with the given string excluding described above.You task is to obtain the minimum possible (lexicographically) string by using these swaps arbitrary number of times (possibly, zero).String $$$a$$$ is lexicographically less than string $$$b$$$ (if strings $$$a$$$ and $$$b$$$ have the same length) if there exists some position $$$i$$$ ($$$1 \le i \le |a|$$$, where $$$|s|$$$ is the length of the string $$$s$$$) such that for every $$$j < i$$$ holds $$$a_j = b_j$$$, and $$$a_i < b_i$$$.",[]556"Bajtek is learning to skate on ice. He's a beginner, so his only mode of transportation is pushing off from a snow drift to the north, east, south or west and sliding until he lands in another snow drift. He has noticed that in this way it's impossible to get from some snow drifts to some other by any sequence of moves. He now wants to heap up some additional snow drifts, so that he can get from any snow drift to any other one. He asked you to find the minimal number of snow drifts that need to be created.We assume that Bajtek can only heap up snow drifts at integer coordinates.",['graphs']557"A sequence of brackets is called balanced if one can turn it into a valid math expression by adding characters '+' and '1'. For example, sequences '(())()', '()', and '(()(()))' are balanced, while ')(', '(()', and '(()))(' are not.You are given a binary string $$$s$$$ of length $$$n$$$. Construct two balanced bracket sequences $$$a$$$ and $$$b$$$ of length $$$n$$$ such that for all $$$1\le i\le n$$$:   if $$$s_i=1$$$, then $$$a_i=b_i$$$  if $$$s_i=0$$$, then $$$a_i\ne b_i$$$ If it is impossible, you should report about it.",[]558"Let's call a positive integer $$$n$$$ ordinary if in the decimal notation all its digits are the same. For example, $$$1$$$, $$$2$$$ and $$$99$$$ are ordinary numbers, but $$$719$$$ and $$$2021$$$ are not ordinary numbers.For a given number $$$n$$$, find the number of ordinary numbers among the numbers from $$$1$$$ to $$$n$$$.","['math', 'number theory']"559"'Jeopardy!' is an intellectual game where players answer questions and earn points. Company Q conducts a simplified 'Jeopardy!' tournament among the best IT companies. By a lucky coincidence, the old rivals made it to the finals: company R1 and company R2. The finals will have n questions, m of them are auction questions and n - m of them are regular questions. Each question has a price. The price of the i-th question is ai points. During the game the players chose the questions. At that, if the question is an auction, then the player who chose it can change the price if the number of his current points is strictly larger than the price of the question. The new price of the question cannot be less than the original price and cannot be greater than the current number of points of the player who chose the question. The correct answer brings the player the points equal to the price of the question. The wrong answer to the question reduces the number of the player's points by the value of the question price.The game will go as follows. First, the R2 company selects a question, then the questions are chosen by the one who answered the previous question correctly. If no one answered the question, then the person who chose last chooses again.All R2 employees support their team. They want to calculate what maximum possible number of points the R2 team can get if luck is on their side during the whole game (they will always be the first to correctly answer questions). Perhaps you are not going to be surprised, but this problem was again entrusted for you to solve.",['math']560"You are given a string $$$s$$$, consisting of lowercase Latin letters. While there is at least one character in the string $$$s$$$ that is repeated at least twice, you perform the following operation:   you choose the index $$$i$$$ ($$$1 \le i \le |s|$$$) such that the character at position $$$i$$$ occurs at least two times in the string $$$s$$$, and delete the character at position $$$i$$$, that is, replace $$$s$$$ with $$$s_1 s_2 \ldots s_{i-1} s_{i+1} s_{i+2} \ldots s_n$$$. For example, if $$$s=$$$""codeforces"", then you can apply the following sequence of operations:   $$$i=6 \Rightarrow s=$$$""codefrces"";  $$$i=1 \Rightarrow s=$$$""odefrces"";  $$$i=7 \Rightarrow s=$$$""odefrcs""; Given a given string $$$s$$$, find the lexicographically maximum string that can be obtained after applying a certain sequence of operations after which all characters in the string become unique.A string $$$a$$$ of length $$$n$$$ is lexicographically less than a string $$$b$$$ of length $$$m$$$, if:   there is an index $$$i$$$ ($$$1 \le i \le \min(n, m)$$$) such that the first $$$i-1$$$ characters of the strings $$$a$$$ and $$$b$$$ are the same, and the $$$i$$$-th character of the string $$$a$$$ is less than $$$i$$$-th character of string $$$b$$$;  or the first $$$\min(n, m)$$$ characters in the strings $$$a$$$ and $$$b$$$ are the same and $$$n < m$$$. For example, the string $$$a=$$$""aezakmi"" is lexicographically less than the string $$$b=$$$""aezus"".",['strings']561"There are $$$n$$$ coins labeled from $$$1$$$ to $$$n$$$. Initially, coin $$$c_i$$$ is on position $$$i$$$ and is facing upwards (($$$c_1, c_2, \dots, c_n)$$$ is a permutation of numbers from $$$1$$$ to $$$n$$$). You can do some operations on these coins. In one operation, you can do the following:Choose $$$2$$$ distinct indices $$$i$$$ and $$$j$$$.Then, swap the coins on positions $$$i$$$ and $$$j$$$.Then, flip both coins on positions $$$i$$$ and $$$j$$$. (If they are initially faced up, they will be faced down after the operation and vice versa)Construct a sequence of at most $$$n+1$$$ operations such that after performing all these operations the coin $$$i$$$ will be on position $$$i$$$ at the end, facing up.Note that you do not need to minimize the number of operations.","['math', 'graphs']"562"Vlad has $$$n$$$ friends, for each of whom he wants to buy one gift for the New Year.There are $$$m$$$ shops in the city, in each of which he can buy a gift for any of his friends. If the $$$j$$$-th friend ($$$1 \le j \le n$$$) receives a gift bought in the shop with the number $$$i$$$ ($$$1 \le i \le m$$$), then the friend receives $$$p_{ij}$$$ units of joy. The rectangular table $$$p_{ij}$$$ is given in the input.Vlad has time to visit at most $$$n-1$$$ shops (where $$$n$$$ is the number of friends). He chooses which shops he will visit and for which friends he will buy gifts in each of them.Let the $$$j$$$-th friend receive $$$a_j$$$ units of joy from Vlad's gift. Let's find the value $$$\alpha=\min\{a_1, a_2, \dots, a_n\}$$$. Vlad's goal is to buy gifts so that the value of $$$\alpha$$$ is as large as possible. In other words, Vlad wants to maximize the minimum of the joys of his friends.For example, let $$$m = 2$$$, $$$n = 2$$$. Let the joy from the gifts that we can buy in the first shop: $$$p_{11} = 1$$$, $$$p_{12}=2$$$, in the second shop: $$$p_{21} = 3$$$, $$$p_{22}=4$$$.Then it is enough for Vlad to go only to the second shop and buy a gift for the first friend, bringing joy $$$3$$$, and for the second — bringing joy $$$4$$$. In this case, the value $$$\alpha$$$ will be equal to $$$\min\{3, 4\} = 3$$$Help Vlad choose gifts for his friends so that the value of $$$\alpha$$$ is as high as possible. Please note that each friend must receive one gift. Vlad can visit at most $$$n-1$$$ shops (where $$$n$$$ is the number of friends). In the shop, he can buy any number of gifts.",[]563"This is the hard version of the problem. The only difference between the two versions is the constraint on $$$n$$$. You can make hacks only if all versions of the problem are solved.A forest is an undirected graph without cycles (not necessarily connected).Mocha and Diana are friends in Zhijiang, both of them have a forest with nodes numbered from $$$1$$$ to $$$n$$$, and they would like to add edges to their forests such that:   After adding edges, both of their graphs are still forests.  They add the same edges. That is, if an edge $$$(u, v)$$$ is added to Mocha's forest, then an edge $$$(u, v)$$$ is added to Diana's forest, and vice versa. Mocha and Diana want to know the maximum number of edges they can add, and which edges to add.","['graphs', 'trees']"564"Do you like summer? Residents of Berland do. They especially love eating ice cream in the hot summer. So this summer day a large queue of n Berland residents lined up in front of the ice cream stall. We know that each of them has a certain amount of berland dollars with them. The residents of Berland are nice people, so each person agrees to swap places with the person right behind him for just 1 dollar. More formally, if person a stands just behind person b, then person a can pay person b 1 dollar, then a and b get swapped. Of course, if person a has zero dollars, he can not swap places with person b.Residents of Berland are strange people. In particular, they get upset when there is someone with a strictly smaller sum of money in the line in front of them.Can you help the residents of Berland form such order in the line so that they were all happy? A happy resident is the one who stands first in the line or the one in front of who another resident stands with not less number of dollars. Note that the people of Berland are people of honor and they agree to swap places only in the manner described above.",[]565You are given two integers $$$n$$$ and $$$d$$$. You need to construct a rooted binary tree consisting of $$$n$$$ vertices with a root at the vertex $$$1$$$ and the sum of depths of all vertices equals to $$$d$$$.A tree is a connected graph without cycles. A rooted tree has a special vertex called the root. A parent of a vertex $$$v$$$ is the last different from $$$v$$$ vertex on the path from the root to the vertex $$$v$$$. The depth of the vertex $$$v$$$ is the length of the path from the root to the vertex $$$v$$$. Children of vertex $$$v$$$ are all vertices for which $$$v$$$ is the parent. The binary tree is such a tree that no vertex has more than $$$2$$$ children.You have to answer $$$t$$$ independent test cases.,['trees']566"You've got a undirected tree s, consisting of n nodes. Your task is to build an optimal T-decomposition for it. Let's define a T-decomposition as follows.Let's denote the set of all nodes s as v. Let's consider an undirected tree t, whose nodes are some non-empty subsets of v, we'll call them xi . The tree t is a T-decomposition of s, if the following conditions holds:  the union of all xi equals v;  for any edge (a, b) of tree s exists the tree node t, containing both a and b;  if the nodes of the tree t xi and xj contain the node a of the tree s, then all nodes of the tree t, lying on the path from xi to xj also contain node a. So this condition is equivalent to the following: all nodes of the tree t, that contain node a of the tree s, form a connected subtree of tree t. There are obviously many distinct trees t, that are T-decompositions of the tree s. For example, a T-decomposition is a tree that consists of a single node, equal to set v.Let's define the cardinality of node xi as the number of nodes in tree s, containing in the node. Let's choose the node with the maximum cardinality in t. Let's assume that its cardinality equals w. Then the weight of T-decomposition t is value w. The optimal T-decomposition is the one with the minimum weight.Your task is to find the optimal T-decomposition of the given tree s that has the minimum number of nodes.","['graphs', 'trees']"567"Nastia has received an array of $$$n$$$ positive integers as a gift.She calls such an array $$$a$$$ good that for all $$$i$$$ ($$$2 \le i \le n$$$) takes place $$$gcd(a_{i - 1}, a_{i}) = 1$$$, where $$$gcd(u, v)$$$ denotes the greatest common divisor (GCD) of integers $$$u$$$ and $$$v$$$.You can perform the operation: select two different indices $$$i, j$$$ ($$$1 \le i, j \le n$$$, $$$i \neq j$$$) and two integers $$$x, y$$$ ($$$1 \le x, y \le 2 \cdot 10^9$$$) so that $$$\min{(a_i, a_j)} = \min{(x, y)}$$$. Then change $$$a_i$$$ to $$$x$$$ and $$$a_j$$$ to $$$y$$$.The girl asks you to make the array good using at most $$$n$$$ operations.It can be proven that this is always possible.","['math', 'number theory']"568"Let's call beauty of an array $$$b_1, b_2, \ldots, b_n$$$ ($$$n > 1$$$)  — $$$\min\limits_{1 \leq i < j \leq n} |b_i - b_j|$$$.You're given an array $$$a_1, a_2, \ldots a_n$$$ and a number $$$k$$$. Calculate the sum of beauty over all subsequences of the array of length exactly $$$k$$$. As this number can be very large, output it modulo $$$998244353$$$.A sequence $$$a$$$ is a subsequence of an array $$$b$$$ if $$$a$$$ can be obtained from $$$b$$$ by deletion of several (possibly, zero or all) elements.",[]569"A magic island Geraldion, where Gerald lives, has its own currency system. It uses banknotes of several values. But the problem is, the system is not perfect and sometimes it happens that Geraldionians cannot express a certain sum of money with any set of banknotes. Of course, they can use any number of banknotes of each value. Such sum is called unfortunate. Gerald wondered: what is the minimum unfortunate sum?",[]570"Having bought his own apartment, Boris decided to paper the walls in every room. Boris's flat has n rooms, each of which has the form of a rectangular parallelepiped. For every room we known its length, width and height of the walls in meters (different rooms can have different dimensions, including height).Boris chose m types of wallpaper to paper the walls of the rooms with (but it is not necessary to use all the types). Each type of wallpaper is sold in rolls of a fixed length and width (the length, naturally, shows how long the unfolded roll will be). In addition, for each type we know the price of one roll of this type.The wallpaper of each type contains strips running along the length of the roll. When gluing the strips must be located strictly vertically (so the roll cannot be rotated, even if the length is less than the width). Besides, a roll can be cut in an arbitrary manner, but the joints of glued pieces should also be vertical. In addition, each room should be papered by only one type of wallpaper. And pieces of the same roll cannot be used to paper different rooms. That is, for each room the rolls are purchased separately. Also, some rolls can be used not completely.After buying an apartment Boris is short of cash, so he wants to spend the minimum money on wallpaper. Help him.",['math']571"There are $$$n + 1$$$ cities, numbered from $$$0$$$ to $$$n$$$. $$$n$$$ roads connect these cities, the $$$i$$$-th road connects cities $$$i - 1$$$ and $$$i$$$ ($$$i \in [1, n]$$$).Each road has a direction. The directions are given by a string of $$$n$$$ characters such that each character is either L or R. If the $$$i$$$-th character is L, it means that the $$$i$$$-th road initially goes from the city $$$i$$$ to the city $$$i - 1$$$; otherwise it goes from the city $$$i - 1$$$ to the city $$$i$$$.A traveler would like to visit as many cities of this country as possible. Initially, they will choose some city to start their journey from. Each day, the traveler must go from the city where they currently are to a neighboring city using one of the roads, and they can go along a road only if it is directed in the same direction they are going; i. e., if a road is directed from city $$$i$$$ to the city $$$i + 1$$$, it is possible to travel from $$$i$$$ to $$$i + 1$$$, but not from $$$i + 1$$$ to $$$i$$$. After the traveler moves to a neighboring city, all roads change their directions to the opposite ones. If the traveler cannot go from their current city to a neighboring city, their journey ends; it is also possible to end the journey whenever the traveler wants to.The goal of the traveler is to visit as many different cities as possible (they can visit a city multiple times, but only the first visit is counted). For each city $$$i$$$, calculate the maximum number of different cities the traveler can visit during exactly one journey if they start in the city $$$i$$$. ",[]572"A famous sculptor Cicasso goes to a world tour!Well, it is not actually a world-wide. But not everyone should have the opportunity to see works of sculptor, shouldn't he? Otherwise there will be no any exclusivity. So Cicasso will entirely hold the world tour in his native country — Berland.Cicasso is very devoted to his work and he wants to be distracted as little as possible. Therefore he will visit only four cities. These cities will be different, so no one could think that he has ""favourites"". Of course, to save money, he will chose the shortest paths between these cities. But as you have probably guessed, Cicasso is a weird person. Although he doesn't like to organize exhibitions, he likes to travel around the country and enjoy its scenery. So he wants the total distance which he will travel to be as large as possible. However, the sculptor is bad in planning, so he asks you for help. There are n cities and m one-way roads in Berland. You have to choose four different cities, which Cicasso will visit and also determine the order in which he will visit them. So that the total distance he will travel, if he visits cities in your order, starting from the first city in your list, and ending in the last, choosing each time the shortest route between a pair of cities — will be the largest. Note that intermediate routes may pass through the cities, which are assigned to the tour, as well as pass twice through the same city. For example, the tour can look like that: . Four cities in the order of visiting marked as overlines: [1, 5, 2, 4].Note that Berland is a high-tech country. So using nanotechnologies all roads were altered so that they have the same length. For the same reason moving using regular cars is not very popular in the country, and it can happen that there are such pairs of cities, one of which generally can not be reached by car from the other one. However, Cicasso is very conservative and cannot travel without the car. Choose cities so that the sculptor can make the tour using only the automobile. It is guaranteed that it is always possible to do. ",['graphs']573"Haiku is a genre of Japanese traditional poetry.A haiku poem consists of 17 syllables split into three phrases, containing 5, 7 and 5 syllables correspondingly (the first phrase should contain exactly 5 syllables, the second phrase should contain exactly 7 syllables, and the third phrase should contain exactly 5 syllables). A haiku masterpiece contains a description of a moment in those three phrases. Every word is important in a small poem, which is why haiku are rich with symbols. Each word has a special meaning, a special role. The main principle of haiku is to say much using a few words.To simplify the matter, in the given problem we will consider that the number of syllable in the phrase is equal to the number of vowel letters there. Only the following letters are regarded as vowel letters: ""a"", ""e"", ""i"", ""o"" and ""u"".Three phases from a certain poem are given. Determine whether it is haiku or not.",['strings']574"This is the hard version of the problem. The difference is that in this version the array contains zeros. You can make hacks only if both versions of the problem are solved.You are given an array $$$[a_1, a_2, \ldots a_n]$$$ consisting of integers $$$-1$$$, $$$0$$$ and $$$1$$$. You have to build a partition of this array into the set of segments $$$[l_1, r_1], [l_2, r_2], \ldots, [l_k, r_k]$$$ with the following property:  Denote the alternating sum of all elements of the $$$i$$$-th segment as $$$s_i$$$: $$$s_i$$$ = $$$a_{l_i} - a_{l_i+1} + a_{l_i+2} - a_{l_i+3} + \ldots \pm a_{r_i}$$$. For example, the alternating sum of elements of segment $$$[2, 4]$$$ in array $$$[1, 0, -1, 1, 1]$$$ equals to $$$0 - (-1) + 1 = 2$$$.  The sum of $$$s_i$$$ over all segments of partition should be equal to zero. Note that each $$$s_i$$$ does not have to be equal to zero, this property is about sum of $$$s_i$$$ over all segments of partition.The set of segments $$$[l_1, r_1], [l_2, r_2], \ldots, [l_k, r_k]$$$ is called a partition of the array $$$a$$$ of length $$$n$$$ if $$$1 = l_1 \le r_1, l_2 \le r_2, \ldots, l_k \le r_k = n$$$ and $$$r_i + 1 = l_{i+1}$$$ for all $$$i = 1, 2, \ldots k-1$$$. In other words, each element of the array must belong to exactly one segment.You have to build a partition of the given array with properties described above or determine that such partition does not exist.Note that it is not required to minimize the number of segments in the partition.",[]575"Mike has a sequence A = [a1, a2, ..., an] of length n. He considers the sequence B = [b1, b2, ..., bn] beautiful if the gcd of all its elements is bigger than 1, i.e. . Mike wants to change his sequence in order to make it beautiful. In one move he can choose an index i (1 ≤ i < n), delete numbers ai, ai + 1 and put numbers ai - ai + 1, ai + ai + 1 in their place instead, in this order. He wants perform as few operations as possible. Find the minimal number of operations to make sequence A beautiful if it's possible, or tell him that it is impossible to do so. is the biggest non-negative number d such that d divides bi for every i (1 ≤ i ≤ n).",['number theory']576"The construction of subway in Bertown is almost finished! The President of Berland will visit this city soon to look at the new subway himself.There are n stations in the subway. It was built according to the Bertown Transport Law:  For each station i there exists exactly one train that goes from this station. Its destination station is pi, possibly pi = i;  For each station i there exists exactly one station j such that pj = i. The President will consider the convenience of subway after visiting it. The convenience is the number of ordered pairs (x, y) such that person can start at station x and, after taking some subway trains (possibly zero), arrive at station y (1 ≤ x, y ≤ n).The mayor of Bertown thinks that if the subway is not convenient enough, then the President might consider installing a new mayor (and, of course, the current mayor doesn't want it to happen). Before President visits the city mayor has enough time to rebuild some paths of subway, thus changing the values of pi for not more than two subway stations. Of course, breaking the Bertown Transport Law is really bad, so the subway must be built according to the Law even after changes.The mayor wants to do these changes in such a way that the convenience of the subway is maximized. Help him to calculate the maximum possible convenience he can get! ",['math']577"Vova decided to clean his room. The room can be represented as the coordinate axis $$$OX$$$. There are $$$n$$$ piles of trash in the room, coordinate of the $$$i$$$-th pile is the integer $$$p_i$$$. All piles have different coordinates.Let's define a total cleanup as the following process. The goal of this process is to collect all the piles in no more than two different $$$x$$$ coordinates. To achieve this goal, Vova can do several (possibly, zero) moves. During one move, he can choose some $$$x$$$ and move all piles from $$$x$$$ to $$$x+1$$$ or $$$x-1$$$ using his broom. Note that he can't choose how many piles he will move.Also, there are two types of queries:  $$$0$$$ $$$x$$$ — remove a pile of trash from the coordinate $$$x$$$. It is guaranteed that there is a pile in the coordinate $$$x$$$ at this moment.  $$$1$$$ $$$x$$$ — add a pile of trash to the coordinate $$$x$$$. It is guaranteed that there is no pile in the coordinate $$$x$$$ at this moment. Note that it is possible that there are zero piles of trash in the room at some moment.Vova wants to know the minimum number of moves he can spend if he wants to do a total cleanup before any queries. He also wants to know this number of moves after applying each query. Queries are applied in the given order. Note that the total cleanup doesn't actually happen and doesn't change the state of piles. It is only used to calculate the number of moves.For better understanding, please read the Notes section below to see an explanation for the first example.",[]578"Polycarp watched TV-show where k jury members one by one rated a participant by adding him a certain number of points (may be negative, i. e. points were subtracted). Initially the participant had some score, and each the marks were one by one added to his score. It is known that the i-th jury member gave ai points.Polycarp does not remember how many points the participant had before this k marks were given, but he remembers that among the scores announced after each of the k judges rated the participant there were n (n ≤ k) values b1, b2, ..., bn (it is guaranteed that all values bj are distinct). It is possible that Polycarp remembers not all of the scores announced, i. e. n < k. Note that the initial score wasn't announced.Your task is to determine the number of options for the score the participant could have before the judges rated the participant.",[]579"Alice gave Bob two integers $$$a$$$ and $$$b$$$ ($$$a > 0$$$ and $$$b \ge 0$$$). Being a curious boy, Bob wrote down an array of non-negative integers with $$$\operatorname{MEX}$$$ value of all elements equal to $$$a$$$ and $$$\operatorname{XOR}$$$ value of all elements equal to $$$b$$$.What is the shortest possible length of the array Bob wrote?Recall that the $$$\operatorname{MEX}$$$ (Minimum EXcluded) of an array is the minimum non-negative integer that does not belong to the array and the $$$\operatorname{XOR}$$$ of an array is the bitwise XOR of all the elements of the array.",[]580"Luntik has decided to try singing. He has $$$a$$$ one-minute songs, $$$b$$$ two-minute songs and $$$c$$$ three-minute songs. He wants to distribute all songs into two concerts such that every song should be included to exactly one concert.He wants to make the absolute difference of durations of the concerts as small as possible. The duration of the concert is the sum of durations of all songs in that concert.Please help Luntik and find the minimal possible difference in minutes between the concerts durations.",['math']581"You are given a non-empty string s consisting of lowercase English letters. You have to pick exactly one non-empty substring of s and shift all its letters 'z'  'y'  'x'  'b'  'a'  'z'. In other words, each character is replaced with the previous character of English alphabet and 'a' is replaced with 'z'.What is the lexicographically minimum string that can be obtained from s by performing this shift exactly once?",['strings']582"You are given $$$n$$$ integers $$$a_1, a_2, \dots, a_n$$$.For each $$$a_i$$$ find its two divisors $$$d_1 > 1$$$ and $$$d_2 > 1$$$ such that $$$\gcd(d_1 + d_2, a_i) = 1$$$ (where $$$\gcd(a, b)$$$ is the greatest common divisor of $$$a$$$ and $$$b$$$) or say that there is no such pair.","['math', 'number theory']"583"You are given $$$n$$$ chips on a number line. The $$$i$$$-th chip is placed at the integer coordinate $$$x_i$$$. Some chips can have equal coordinates.You can perform each of the two following types of moves any (possibly, zero) number of times on any chip:  Move the chip $$$i$$$ by $$$2$$$ to the left or $$$2$$$ to the right for free (i.e. replace the current coordinate $$$x_i$$$ with $$$x_i - 2$$$ or with $$$x_i + 2$$$);  move the chip $$$i$$$ by $$$1$$$ to the left or $$$1$$$ to the right and pay one coin for this move (i.e. replace the current coordinate $$$x_i$$$ with $$$x_i - 1$$$ or with $$$x_i + 1$$$). Note that it's allowed to move chips to any integer coordinate, including negative and zero.Your task is to find the minimum total number of coins required to move all $$$n$$$ chips to the same coordinate (i.e. all $$$x_i$$$ should be equal after some sequence of moves).",['math']584"Let's call the following process a transformation of a sequence of length $$$n$$$.If the sequence is empty, the process ends. Otherwise, append the greatest common divisor (GCD) of all the elements of the sequence to the result and remove one arbitrary element from the sequence. Thus, when the process ends, we have a sequence of $$$n$$$ integers: the greatest common divisors of all the elements in the sequence before each deletion.You are given an integer sequence $$$1, 2, \dots, n$$$. Find the lexicographically maximum result of its transformation.A sequence $$$a_1, a_2, \ldots, a_n$$$ is lexicographically larger than a sequence $$$b_1, b_2, \ldots, b_n$$$, if there is an index $$$i$$$ such that $$$a_j = b_j$$$ for all $$$j < i$$$, and $$$a_i > b_i$$$.",['math']585"Of course our child likes walking in a zoo. The zoo has n areas, that are numbered from 1 to n. The i-th area contains ai animals in it. Also there are m roads in the zoo, and each road connects two distinct areas. Naturally the zoo is connected, so you can reach any area of the zoo from any other area using the roads.Our child is very smart. Imagine the child want to go from area p to area q. Firstly he considers all the simple routes from p to q. For each route the child writes down the number, that is equal to the minimum number of animals among the route areas. Let's denote the largest of the written numbers as f(p, q). Finally, the child chooses one of the routes for which he writes down the value f(p, q).After the child has visited the zoo, he thinks about the question: what is the average value of f(p, q) for all pairs p, q (p ≠ q)? Can you answer his question?",[]586"You are given $$$n$$$ of integers $$$a_1, a_2, \ldots, a_n$$$. Process $$$q$$$ queries of two types: query of the form ""0 $$$x_j$$$"": add the value $$$x_j$$$ to all even elements of the array $$$a$$$, query of the form ""1 $$$x_j$$$"": add the value $$$x_j$$$ to all odd elements of the array $$$a$$$.Note that when processing the query, we look specifically at the odd/even value of $$$a_i$$$, not its index.After processing each query, print the sum of the elements of the array $$$a$$$.Please note that the answer for some test cases won't fit into 32-bit integer type, so you should use at least 64-bit integer type in your programming language (like long long for C++).",['math']587"You have been blessed as a child of Omkar. To express your gratitude, please solve this problem for Omkar!An array $$$a$$$ of length $$$n$$$ is called complete if all elements are positive and don't exceed $$$1000$$$, and for all indices $$$x$$$,$$$y$$$,$$$z$$$ ($$$1 \leq x,y,z \leq n$$$), $$$a_{x}+a_{y} \neq a_{z}$$$ (not necessarily distinct).You are given one integer $$$n$$$. Please find any complete array of length $$$n$$$. It is guaranteed that under given constraints such array exists.",[]588"You have an array $$$a$$$ of length $$$n$$$. You can exactly once select an integer $$$len$$$ between $$$1$$$ and $$$n - 1$$$ inclusively, and then sort in non-decreasing order the prefix of the array of length $$$len$$$ and the suffix of the array of length $$$n - len$$$ independently.For example, if the array is $$$a = [3, 1, 4, 5, 2]$$$, and you choose $$$len = 2$$$, then after that the array will be equal to $$$[1, 3, 2, 4, 5]$$$.Could it be that after performing this operation, the array will not be sorted in non-decreasing order?",[]589"There are $$$n$$$ weighted points on the $$$OX$$$-axis. The coordinate and the weight of the $$$i$$$-th point is $$$x_i$$$ and $$$w_i$$$, respectively. All points have distinct coordinates and positive weights. Also, $$$x_i < x_{i + 1}$$$ holds for any $$$1 \leq i < n$$$. The weighted distance between $$$i$$$-th point and $$$j$$$-th point is defined as $$$|x_i - x_j| \cdot (w_i + w_j)$$$, where $$$|val|$$$ denotes the absolute value of $$$val$$$.You should answer $$$q$$$ queries, where the $$$i$$$-th query asks the following: Find the minimum weighted distance among all pairs of distinct points among the points in subarray $$$[l_i,r_i]$$$.",[]590"Let there be an array $$$b_1, b_2, \ldots, b_k$$$. Let there be a partition of this array into segments $$$[l_1; r_1], [l_2; r_2], \ldots, [l_c; r_c]$$$, where $$$l_1 = 1$$$, $$$r_c = k$$$, and for any $$$2 \leq i \leq c$$$ holds that $$$r_{i-1} + 1 = l_i$$$. In other words, each element of the array belongs to exactly one segment.Let's define the cost of a partition as $$$$$$c + \sum_{i = 1}^{c} \operatorname{mex}(\{b_{l_i}, b_{l_i + 1}, \ldots, b_{r_i}\}),$$$$$$ where $$$\operatorname{mex}$$$ of a set of numbers $$$S$$$ is the smallest non-negative integer that does not occur in the set $$$S$$$. In other words, the cost of a partition is the number of segments plus the sum of MEX over all segments. Let's define the value of an array $$$b_1, b_2, \ldots, b_k$$$ as the maximum possible cost over all partitions of this array.You are given an array $$$a$$$ of size $$$n$$$. Find the sum of values of all its subsegments.An array $$$x$$$ is a subsegment of an array $$$y$$$ if $$$x$$$ can be obtained from $$$y$$$ by deletion of several (possibly, zero or all) elements from the beginning and several (possibly, zero or all) elements from the end.",['math']591"Given $$$n$$$ integers $$$a_1, a_2, \dots, a_n$$$. You can perform the following operation on them:  select any element $$$a_i$$$ ($$$1 \le i \le n$$$) and divide it by $$$2$$$ (round down). In other words, you can replace any selected element $$$a_i$$$ with the value $$$\left \lfloor \frac{a_i}{2}\right\rfloor$$$ (where $$$\left \lfloor x \right\rfloor$$$ is – round down the real number $$$x$$$). Output the minimum number of operations that must be done for a sequence of integers to become strictly increasing (that is, for the condition $$$a_1 \lt a_2 \lt \dots \lt a_n$$$ to be satisfied). Or determine that it is impossible to obtain such a sequence. Note that elements cannot be swapped. The only possible operation is described above.For example, let $$$n = 3$$$ and a sequence of numbers $$$[3, 6, 5]$$$ be given. Then it is enough to perform two operations on it:   Write the number $$$\left \lfloor \frac{6}{2}\right\rfloor = 3$$$ instead of the number $$$a_2=6$$$ and get the sequence $$$[3, 3, 5]$$$;  Then replace $$$a_1=3$$$ with $$$\left \lfloor \frac{3}{2}\right\rfloor = 1$$$ and get the sequence $$$[1, 3, 5]$$$. The resulting sequence is strictly increasing because $$$1 \lt 3 \lt 5$$$.",[]592"After all the events in Orlando we all know, Sasha and Roma decided to find out who is still the team's biggest loser. Thankfully, Masha found somewhere a revolver with a rotating cylinder of n bullet slots able to contain exactly k bullets, now the boys have a chance to resolve the problem once and for all. Sasha selects any k out of n slots he wishes and puts bullets there. Roma spins the cylinder so that every of n possible cylinder's shifts is equiprobable. Then the game starts, the players take turns, Sasha starts: he puts the gun to his head and shoots. If there was no bullet in front of the trigger, the cylinder shifts by one position and the weapon is given to Roma for make the same move. The game continues until someone is shot, the survivor is the winner. Sasha does not want to lose, so he must choose slots for bullets in such a way as to minimize the probability of its own loss. Of all the possible variant he wants to select the lexicographically minimal one, where an empty slot is lexicographically less than a charged one. More formally, the cylinder of n bullet slots able to contain k bullets can be represented as a string of n characters. Exactly k of them are ""X"" (charged slots) and the others are ""."" (uncharged slots). Let us describe the process of a shot. Suppose that the trigger is in front of the first character of the string (the first slot). If a shot doesn't kill anyone and the cylinder shifts, then the string shifts left. So the first character becomes the last one, the second character becomes the first one, and so on. But the trigger doesn't move. It will be in front of the first character of the resulting string.Among all the strings that give the minimal probability of loss, Sasha choose the lexicographically minimal one. According to this very string, he charges the gun. You have to help Sasha to charge the gun. For that, each xi query must be answered: is there a bullet in the positions xi?",['math']593"Each New Year Timofey and his friends cut down a tree of n vertices and bring it home. After that they paint all the n its vertices, so that the i-th vertex gets color ci.Now it's time for Timofey birthday, and his mother asked him to remove the tree. Timofey removes the tree in the following way: he takes some vertex in hands, while all the other vertices move down so that the tree becomes rooted at the chosen vertex. After that Timofey brings the tree to a trash can.Timofey doesn't like it when many colors are mixing together. A subtree annoys him if there are vertices of different color in it. Timofey wants to find a vertex which he should take in hands so that there are no subtrees that annoy him. He doesn't consider the whole tree as a subtree since he can't see the color of the root vertex.A subtree of some vertex is a subgraph containing that vertex and all its descendants.Your task is to determine if there is a vertex, taking which in hands Timofey wouldn't be annoyed.","['graphs', 'trees']"594"You are given a pair of integers $$$(a, b)$$$ and an integer $$$x$$$.You can change the pair in two different ways:   set (assign) $$$a := |a - b|$$$;  set (assign) $$$b := |a - b|$$$,  where $$$|a - b|$$$ is the absolute difference between $$$a$$$ and $$$b$$$.The pair $$$(a, b)$$$ is called $$$x$$$-magic if $$$x$$$ is obtainable either as $$$a$$$ or as $$$b$$$ using only the given operations (i.e. the pair $$$(a, b)$$$ is $$$x$$$-magic if $$$a = x$$$ or $$$b = x$$$ after some number of operations applied). You can apply the operations any number of times (even zero).Your task is to find out if the pair $$$(a, b)$$$ is $$$x$$$-magic or not.You have to answer $$$t$$$ independent test cases.","['math', 'number theory']"595"Alice and Bob play a game. They have a binary string $$$s$$$ (a string such that each character in it is either $$$0$$$ or $$$1$$$). Alice moves first, then Bob, then Alice again, and so on.During their move, the player can choose any number (not less than one) of consecutive equal characters in $$$s$$$ and delete them.For example, if the string is $$$10110$$$, there are $$$6$$$ possible moves (deleted characters are bold):  $$$\textbf{1}0110 \to 0110$$$;  $$$1\textbf{0}110 \to 1110$$$;  $$$10\textbf{1}10 \to 1010$$$;  $$$101\textbf{1}0 \to 1010$$$;  $$$10\textbf{11}0 \to 100$$$;  $$$1011\textbf{0} \to 1011$$$. After the characters are removed, the characters to the left and to the right of the removed block become adjacent. I. e. the following sequence of moves is valid: $$$10\textbf{11}0 \to 1\textbf{00} \to 1$$$.The game ends when the string becomes empty, and the score of each player is the number of $$$1$$$-characters deleted by them.Each player wants to maximize their score. Calculate the resulting score of Alice.",['games']596"Nastia has $$$2$$$ positive integers $$$A$$$ and $$$B$$$. She defines that:  The integer is good if it is divisible by $$$A \cdot B$$$;  Otherwise, the integer is nearly good, if it is divisible by $$$A$$$. For example, if $$$A = 6$$$ and $$$B = 4$$$, the integers $$$24$$$ and $$$72$$$ are good, the integers $$$6$$$, $$$660$$$ and $$$12$$$ are nearly good, the integers $$$16$$$, $$$7$$$ are neither good nor nearly good.Find $$$3$$$ different positive integers $$$x$$$, $$$y$$$, and $$$z$$$ such that exactly one of them is good and the other $$$2$$$ are nearly good, and $$$x + y = z$$$.","['math', 'number theory']"597"Vasya likes taking part in Codeforces contests. When a round is over, Vasya follows all submissions in the system testing tab.There are $$$n$$$ solutions, the $$$i$$$-th of them should be tested on $$$a_i$$$ tests, testing one solution on one test takes $$$1$$$ second. The solutions are judged in the order from $$$1$$$ to $$$n$$$. There are $$$k$$$ testing processes which test solutions simultaneously. Each of them can test at most one solution at a time.At any time moment $$$t$$$ when some testing process is not judging any solution, it takes the first solution from the queue and tests it on each test in increasing order of the test ids. Let this solution have id $$$i$$$, then it is being tested on the first test from time moment $$$t$$$ till time moment $$$t + 1$$$, then on the second test till time moment $$$t + 2$$$ and so on. This solution is fully tested at time moment $$$t + a_i$$$, and after that the testing process immediately starts testing another solution.Consider some time moment, let there be exactly $$$m$$$ fully tested solutions by this moment. There is a caption ""System testing: $$$d$$$%"" on the page with solutions, where $$$d$$$ is calculated as$$$$$$d = round\left(100\cdot\frac{m}{n}\right),$$$$$$where $$$round(x) = \lfloor{x + 0.5}\rfloor$$$ is a function which maps every real to the nearest integer.Vasya calls a submission interesting if there is a time moment (possibly, non-integer) when the solution is being tested on some test $$$q$$$, and the caption says ""System testing: $$$q$$$%"". Find the number of interesting solutions.Please note that in case when multiple processes attempt to take the first submission from the queue at the same moment (for instance, at the initial moment), the order they take the solutions does not matter.",[]598"Another programming contest is over. You got hold of the contest's final results table. The table has the following data. For each team we are shown two numbers: the number of problems and the total penalty time. However, for no team we are shown its final place.You know the rules of comparing the results of two given teams very well. Let's say that team a solved pa problems with total penalty time ta and team b solved pb problems with total penalty time tb. Team a gets a higher place than team b in the end, if it either solved more problems on the contest, or solved the same number of problems but in less total time. In other words, team a gets a higher place than team b in the final results' table if either pa > pb, or pa = pb and ta < tb. It is considered that the teams that solve the same number of problems with the same penalty time share all corresponding places. More formally, let's say there is a group of x teams that solved the same number of problems with the same penalty time. Let's also say that y teams performed better than the teams from this group. In this case all teams from the group share places y + 1, y + 2, ..., y + x. The teams that performed worse than the teams from this group, get their places in the results table starting from the y + x + 1-th place.Your task is to count what number of teams from the given list shared the k-th place. ",[]599"The Narrator has an integer array $$$a$$$ of length $$$n$$$, but he will only tell you the size $$$n$$$ and $$$q$$$ statements, each of them being three integers $$$i, j, x$$$, which means that $$$a_i \mid a_j = x$$$, where $$$|$$$ denotes the bitwise OR operation.Find the lexicographically smallest array $$$a$$$ that satisfies all the statements.An array $$$a$$$ is lexicographically smaller than an array $$$b$$$ of the same length if and only if the following holds:   in the first position where $$$a$$$ and $$$b$$$ differ, the array $$$a$$$ has a smaller element than the corresponding element in $$$b$$$. ",['graphs']600"Ashish and Vivek play a game on a matrix consisting of $$$n$$$ rows and $$$m$$$ columns, where they take turns claiming cells. Unclaimed cells are represented by $$$0$$$, while claimed cells are represented by $$$1$$$. The initial state of the matrix is given. There can be some claimed cells in the initial state.In each turn, a player must claim a cell. A cell may be claimed if it is unclaimed and does not share a row or column with any other already claimed cells. When a player is unable to make a move, he loses and the game ends.If Ashish and Vivek take turns to move and Ashish goes first, determine the winner of the game if both of them are playing optimally.Optimal play between two players means that both players choose the best possible strategy to achieve the best possible outcome for themselves.",['games']601"Tanya wants to go on a journey across the cities of Berland. There are $$$n$$$ cities situated along the main railroad line of Berland, and these cities are numbered from $$$1$$$ to $$$n$$$. Tanya plans her journey as follows. First of all, she will choose some city $$$c_1$$$ to start her journey. She will visit it, and after that go to some other city $$$c_2 > c_1$$$, then to some other city $$$c_3 > c_2$$$, and so on, until she chooses to end her journey in some city $$$c_k > c_{k - 1}$$$. So, the sequence of visited cities $$$[c_1, c_2, \dots, c_k]$$$ should be strictly increasing.There are some additional constraints on the sequence of cities Tanya visits. Each city $$$i$$$ has a beauty value $$$b_i$$$ associated with it. If there is only one city in Tanya's journey, these beauty values imply no additional constraints. But if there are multiple cities in the sequence, then for any pair of adjacent cities $$$c_i$$$ and $$$c_{i + 1}$$$, the condition $$$c_{i + 1} - c_i = b_{c_{i + 1}} - b_{c_i}$$$ must hold.For example, if $$$n = 8$$$ and $$$b = [3, 4, 4, 6, 6, 7, 8, 9]$$$, there are several three possible ways to plan a journey:  $$$c = [1, 2, 4]$$$;  $$$c = [3, 5, 6, 8]$$$;  $$$c = [7]$$$ (a journey consisting of one city is also valid). There are some additional ways to plan a journey that are not listed above.Tanya wants her journey to be as beautiful as possible. The beauty value of the whole journey is the sum of beauty values over all visited cities. Can you help her to choose the optimal plan, that is, to maximize the beauty value of the journey?",[]602"You are given a string $$$s$$$. Each character is either 0 or 1.You want all 1's in the string to form a contiguous subsegment. For example, if the string is 0, 1, 00111 or 01111100, then all 1's form a contiguous subsegment, and if the string is 0101, 100001 or 11111111111101, then this condition is not met.You may erase some (possibly none) 0's from the string. What is the minimum number of 0's that you have to erase?",['strings']603"You are given an integer sequence $$$a_1, a_2, \dots, a_n$$$.Find the number of pairs of indices $$$(l, r)$$$ ($$$1 \le l \le r \le n$$$) such that the value of median of $$$a_l, a_{l+1}, \dots, a_r$$$ is exactly the given number $$$m$$$.The median of a sequence is the value of an element which is in the middle of the sequence after sorting it in non-decreasing order. If the length of the sequence is even, the left of two middle elements is used.For example, if $$$a=[4, 2, 7, 5]$$$ then its median is $$$4$$$ since after sorting the sequence, it will look like $$$[2, 4, 5, 7]$$$ and the left of two middle elements is equal to $$$4$$$. The median of $$$[7, 1, 2, 9, 6]$$$ equals $$$6$$$ since after sorting, the value $$$6$$$ will be in the middle of the sequence.Write a program to find the number of pairs of indices $$$(l, r)$$$ ($$$1 \le l \le r \le n$$$) such that the value of median of $$$a_l, a_{l+1}, \dots, a_r$$$ is exactly the given number $$$m$$$.",[]604"Vova plays a computer game known as Mages and Monsters. Vova's character is a mage. Though as he has just started, his character knows no spells.Vova's character can learn new spells during the game. Every spell is characterized by two values xi and yi — damage per second and mana cost per second, respectively. Vova doesn't have to use a spell for an integer amount of seconds. More formally, if he uses a spell with damage x and mana cost y for z seconds, then he will deal x·z damage and spend y·z mana (no rounding). If there is no mana left (mana amount is set in the start of the game and it remains the same at the beginning of every fight), then character won't be able to use any spells. It is prohibited to use multiple spells simultaneously.Also Vova can fight monsters. Every monster is characterized by two values tj and hj — monster kills Vova's character in tj seconds and has hj health points. Mana refills after every fight (or Vova's character revives with full mana reserve), so previous fights have no influence on further ones.Vova's character kills a monster, if he deals hj damage to it in no more than tj seconds using his spells (it is allowed to use more than one spell in a fight) and spending no more mana than he had at the beginning of the fight. If monster's health becomes zero exactly in tj seconds (it means that the monster and Vova's character kill each other at the same time), then Vova wins the fight.You have to write a program which can answer two types of queries:  1 x y — Vova's character learns new spell which deals x damage per second and costs y mana per second.  2 t h — Vova fights the monster which kills his character in t seconds and has h health points. Note that queries are given in a different form. Also remember that Vova's character knows no spells at the beginning of the game.For every query of second type you have to determine if Vova is able to win the fight with corresponding monster.",['geometry']605"An infinitely long railway has a train consisting of n cars, numbered from 1 to n (the numbers of all the cars are distinct) and positioned in arbitrary order. David Blaine wants to sort the railway cars in the order of increasing numbers. In one move he can make one of the cars disappear from its place and teleport it either to the beginning of the train, or to the end of the train, at his desire. What is the minimum number of actions David Blaine needs to perform in order to sort the train?",[]606"Little Petya very much likes rectangles and especially squares. Recently he has received 8 points on the plane as a gift from his mother. The points are pairwise distinct. Petya decided to split them into two sets each containing 4 points so that the points from the first set lay at the vertexes of some square and the points from the second set lay at the vertexes of a rectangle. Each point of initial 8 should belong to exactly one set. It is acceptable for a rectangle from the second set was also a square. If there are several partitions, Petya will be satisfied by any of them. Help him find such partition. Note that the rectangle and the square from the partition should have non-zero areas. The sides of the figures do not have to be parallel to the coordinate axes, though it might be the case.","['math', 'geometry']"607"Egor has a table of size $$$n \times m$$$, with lines numbered from $$$1$$$ to $$$n$$$ and columns numbered from $$$1$$$ to $$$m$$$. Each cell has a color that can be presented as an integer from $$$1$$$ to $$$10^5$$$.Let us denote the cell that lies in the intersection of the $$$r$$$-th row and the $$$c$$$-th column as $$$(r, c)$$$. We define the manhattan distance between two cells $$$(r_1, c_1)$$$ and $$$(r_2, c_2)$$$ as the length of a shortest path between them where each consecutive cells in the path must have a common side. The path can go through cells of any color. For example, in the table $$$3 \times 4$$$ the manhattan distance between $$$(1, 2)$$$ and $$$(3, 3)$$$ is $$$3$$$, one of the shortest paths is the following: $$$(1, 2) \to (2, 2) \to (2, 3) \to (3, 3)$$$. Egor decided to calculate the sum of manhattan distances between each pair of cells of the same color. Help him to calculate this sum.",['math']608"Polycarp plays a well-known computer game (we won't mention its name). In this game, he can craft tools of two types — shovels and swords. To craft a shovel, Polycarp spends two sticks and one diamond; to craft a sword, Polycarp spends two diamonds and one stick.Each tool can be sold for exactly one emerald. How many emeralds can Polycarp earn, if he has $$$a$$$ sticks and $$$b$$$ diamonds?",['math']609"Thanos wants to destroy the avengers base, but he needs to destroy the avengers along with their base.Let we represent their base with an array, where each position can be occupied by many avengers, but one avenger can occupy only one position. Length of their base is a perfect power of $$$2$$$. Thanos wants to destroy the base using minimum power. He starts with the whole base and in one step he can do either of following:   if the current length is at least $$$2$$$, divide the base into $$$2$$$ equal halves and destroy them separately, or  burn the current base. If it contains no avenger in it, it takes $$$A$$$ amount of power, otherwise it takes his $$$B \cdot n_a \cdot l$$$ amount of power, where $$$n_a$$$ is the number of avengers and $$$l$$$ is the length of the current base. Output the minimum power needed by Thanos to destroy the avengers' base.",['math']610"Alice and Bob are playing yet another card game. This time the rules are the following. There are $$$n$$$ cards lying in a row in front of them. The $$$i$$$-th card has value $$$a_i$$$. First, Alice chooses a non-empty consecutive segment of cards $$$[l; r]$$$ ($$$l \le r$$$). After that Bob removes a single card $$$j$$$ from that segment $$$(l \le j \le r)$$$. The score of the game is the total value of the remaining cards on the segment $$$(a_l + a_{l + 1} + \dots + a_{j - 1} + a_{j + 1} + \dots + a_{r - 1} + a_r)$$$. In particular, if Alice chooses a segment with just one element, then the score after Bob removes the only card is $$$0$$$.Alice wants to make the score as big as possible. Bob takes such a card that the score is as small as possible.What segment should Alice choose so that the score is maximum possible? Output the maximum score.",[]611"Kate has a set $$$S$$$ of $$$n$$$ integers $$$\{1, \dots, n\} $$$. She thinks that imperfection of a subset $$$M \subseteq S$$$ is equal to the maximum of $$$gcd(a, b)$$$ over all pairs $$$(a, b)$$$ such that both $$$a$$$ and $$$b$$$ are in $$$M$$$ and $$$a \neq b$$$. Kate is a very neat girl and for each $$$k \in \{2, \dots, n\}$$$ she wants to find a subset that has the smallest imperfection among all subsets in $$$S$$$ of size $$$k$$$. There can be more than one subset with the smallest imperfection and the same size, but you don't need to worry about it. Kate wants to find all the subsets herself, but she needs your help to find the smallest possible imperfection for each size $$$k$$$, will name it $$$I_k$$$. Please, help Kate to find $$$I_2$$$, $$$I_3$$$, ..., $$$I_n$$$.","['math', 'number theory']"612"After a hard day Vitaly got very hungry and he wants to eat his favorite potato pie. But it's not that simple. Vitaly is in the first room of the house with n room located in a line and numbered starting from one from left to right. You can go from the first room to the second room, from the second room to the third room and so on — you can go from the (n - 1)-th room to the n-th room. Thus, you can go to room x only from room x - 1.The potato pie is located in the n-th room and Vitaly needs to go there. Each pair of consecutive rooms has a door between them. In order to go to room x from room x - 1, you need to open the door between the rooms with the corresponding key. In total the house has several types of doors (represented by uppercase Latin letters) and several types of keys (represented by lowercase Latin letters). The key of type t can open the door of type T if and only if t and T are the same letter, written in different cases. For example, key f can open door F.Each of the first n - 1 rooms contains exactly one key of some type that Vitaly can use to get to next rooms. Once the door is open with some key, Vitaly won't get the key from the keyhole but he will immediately run into the next room. In other words, each key can open no more than one door.Vitaly realizes that he may end up in some room without the key that opens the door to the next room. Before the start his run for the potato pie Vitaly can buy any number of keys of any type that is guaranteed to get to room n.Given the plan of the house, Vitaly wants to know what is the minimum number of keys he needs to buy to surely get to the room n, which has a delicious potato pie. Write a program that will help Vitaly find out this number.",['strings']613"Marcin is a coach in his university. There are $$$n$$$ students who want to attend a training camp. Marcin is a smart coach, so he wants to send only the students that can work calmly with each other.Let's focus on the students. They are indexed with integers from $$$1$$$ to $$$n$$$. Each of them can be described with two integers $$$a_i$$$ and $$$b_i$$$; $$$b_i$$$ is equal to the skill level of the $$$i$$$-th student (the higher, the better). Also, there are $$$60$$$ known algorithms, which are numbered with integers from $$$0$$$ to $$$59$$$. If the $$$i$$$-th student knows the $$$j$$$-th algorithm, then the $$$j$$$-th bit ($$$2^j$$$) is set in the binary representation of $$$a_i$$$. Otherwise, this bit is not set.Student $$$x$$$ thinks that he is better than student $$$y$$$ if and only if $$$x$$$ knows some algorithm which $$$y$$$ doesn't know. Note that two students can think that they are better than each other. A group of students can work together calmly if no student in this group thinks that he is better than everyone else in this group.Marcin wants to send a group of at least two students which will work together calmly and will have the maximum possible sum of the skill levels. What is this sum?",['graphs']614"As the name of the task implies, you are asked to do some work with segments and trees.Recall that a tree is a connected undirected graph such that there is exactly one simple path between every pair of its vertices.You are given $$$n$$$ segments $$$[l_1, r_1], [l_2, r_2], \dots, [l_n, r_n]$$$, $$$l_i < r_i$$$ for every $$$i$$$. It is guaranteed that all segments' endpoints are integers, and all endpoints are unique — there is no pair of segments such that they start in the same point, end in the same point or one starts in the same point the other one ends.Let's generate a graph with $$$n$$$ vertices from these segments. Vertices $$$v$$$ and $$$u$$$ are connected by an edge if and only if segments $$$[l_v, r_v]$$$ and $$$[l_u, r_u]$$$ intersect and neither of it lies fully inside the other one.For example, pairs $$$([1, 3], [2, 4])$$$ and $$$([5, 10], [3, 7])$$$ will induce the edges but pairs $$$([1, 2], [3, 4])$$$ and $$$([5, 7], [3, 10])$$$ will not.Determine if the resulting graph is a tree or not.","['graphs', 'trees']"615"There are $$$n$$$ distinct points on a coordinate line, the coordinate of $$$i$$$-th point equals to $$$x_i$$$. Choose a subset of the given set of points such that the distance between each pair of points in a subset is an integral power of two. It is necessary to consider each pair of points, not only adjacent. Note that any subset containing one element satisfies the condition above. Among all these subsets, choose a subset with maximum possible size.In other words, you have to choose the maximum possible number of points $$$x_{i_1}, x_{i_2}, \dots, x_{i_m}$$$ such that for each pair $$$x_{i_j}$$$, $$$x_{i_k}$$$ it is true that $$$|x_{i_j} - x_{i_k}| = 2^d$$$ where $$$d$$$ is some non-negative integer number (not necessarily the same for each pair of points).",['math']616"Recently Pashmak has been employed in a transportation company. The company has k buses and has a contract with a school which has n students. The school planned to take the students to d different places for d days (each day in one place). Each day the company provides all the buses for the trip. Pashmak has to arrange the students in the buses. He wants to arrange the students in a way that no two students become close friends. In his ridiculous idea, two students will become close friends if and only if they are in the same buses for all d days.Please help Pashmak with his weird idea. Assume that each bus has an unlimited capacity.",['math']617"Berland SU holds yet another training contest for its students today. $$$n$$$ students came, each of them brought his laptop. However, it turned out that everyone has forgot their chargers!Let students be numbered from $$$1$$$ to $$$n$$$. Laptop of the $$$i$$$-th student has charge $$$a_i$$$ at the beginning of the contest and it uses $$$b_i$$$ of charge per minute (i.e. if the laptop has $$$c$$$ charge at the beginning of some minute, it becomes $$$c - b_i$$$ charge at the beginning of the next minute). The whole contest lasts for $$$k$$$ minutes.Polycarp (the coach of Berland SU) decided to buy a single charger so that all the students would be able to successfully finish the contest. He buys the charger at the same moment the contest starts.Polycarp can choose to buy the charger with any non-negative (zero or positive) integer power output. The power output is chosen before the purchase, it can't be changed afterwards. Let the chosen power output be $$$x$$$. At the beginning of each minute (from the minute contest starts to the last minute of the contest) he can plug the charger into any of the student's laptops and use it for some integer number of minutes. If the laptop is using $$$b_i$$$ charge per minute then it will become $$$b_i - x$$$ per minute while the charger is plugged in. Negative power usage rate means that the laptop's charge is increasing. The charge of any laptop isn't limited, it can become infinitely large. The charger can be plugged in no more than one laptop at the same time.The student successfully finishes the contest if the charge of his laptop never is below zero at the beginning of some minute (from the minute contest starts to the last minute of the contest, zero charge is allowed). The charge of the laptop of the minute the contest ends doesn't matter.Help Polycarp to determine the minimal possible power output the charger should have so that all the students are able to successfully finish the contest. Also report if no such charger exists.",[]618"A tree is a connected undirected graph consisting of n vertices and n  -  1 edges. Vertices are numbered 1 through n.Limak is a little polar bear. He once had a tree with n vertices but he lost it. He still remembers something about the lost tree though.You are given m pairs of vertices (a1, b1), (a2, b2), ..., (am, bm). Limak remembers that for each i there was no edge between ai and bi. He also remembers that vertex 1 was incident to exactly k edges (its degree was equal to k).Is it possible that Limak remembers everything correctly? Check whether there exists a tree satisfying the given conditions.","['graphs', 'trees']"619"You are given $$$n$$$ intervals in form $$$[l; r]$$$ on a number line.You are also given $$$m$$$ queries in form $$$[x; y]$$$. What is the minimal number of intervals you have to take so that every point (not necessarily integer) from $$$x$$$ to $$$y$$$ is covered by at least one of them? If you can't choose intervals so that every point from $$$x$$$ to $$$y$$$ is covered, then print -1 for that query.",['trees']620"The Berland capital is shaken with three bold crimes committed by the Pihsters, a notorious criminal gang.The Berland capital's map is represented by an n × m rectangular table. Each cell of the table on the map represents some districts of the capital. The capital's main detective Polycarpus took a map and marked there the districts where the first three robberies had been committed as asterisks. Deduction tells Polycarpus that the fourth robbery will be committed in such district, that all four robbed districts will form the vertices of some rectangle, parallel to the sides of the map. Polycarpus is good at deduction but he's hopeless at math. So he asked you to find the district where the fourth robbery will be committed.",['geometry']621"You are given $$$n$$$ numbers $$$a_1, a_2, \ldots, a_n$$$. Is it possible to arrange them in a circle in such a way that every number is strictly less than the sum of its neighbors?For example, for the array $$$[1, 4, 5, 6, 7, 8]$$$, the arrangement on the left is valid, while arrangement on the right is not, as $$$5\ge 4 + 1$$$ and $$$8> 1 + 6$$$.  ",['math']622"The polar bears are going fishing. They plan to sail from (sx, sy) to (ex, ey). However, the boat can only sail by wind. At each second, the wind blows in one of these directions: east, south, west or north. Assume the boat is currently at (x, y).  If the wind blows to the east, the boat will move to (x + 1, y).  If the wind blows to the south, the boat will move to (x, y - 1).  If the wind blows to the west, the boat will move to (x - 1, y).  If the wind blows to the north, the boat will move to (x, y + 1). Alternatively, they can hold the boat by the anchor. In this case, the boat stays at (x, y). Given the wind direction for t seconds, what is the earliest time they sail to (ex, ey)?",[]623"In a medieval kingdom, the economic crisis is raging. Milk drops fall, Economic indicators are deteriorating every day, money from the treasury disappear. To remedy the situation, King Charles Sunnyface decided make his n sons-princes marry the brides with as big dowry as possible.In search of candidates, the king asked neighboring kingdoms, and after a while several delegations arrived with m unmarried princesses. Receiving guests, Karl learned that the dowry of the i th princess is wi of golden coins. Although the action takes place in the Middle Ages, progressive ideas are widespread in society, according to which no one can force a princess to marry a prince whom she does not like. Therefore, each princess has an opportunity to choose two princes, for each of which she is ready to become a wife. The princes were less fortunate, they will obey the will of their father in the matter of choosing a bride.Knowing the value of the dowry and the preferences of each princess, Charles wants to play weddings in such a way that the total dowry of the brides of all his sons would be as great as possible. At the same time to marry all the princes or princesses is not necessary. Each prince can marry no more than one princess, and vice versa, each princess can marry no more than one prince.Help the king to organize the marriage of his sons in the most profitable way for the treasury.",['graphs']624"Bearland has n cities, numbered 1 through n. Cities are connected via bidirectional roads. Each road connects two distinct cities. No two roads connect the same pair of cities.Bear Limak was once in a city a and he wanted to go to a city b. There was no direct connection so he decided to take a long walk, visiting each city exactly once. Formally:   There is no road between a and b.  There exists a sequence (path) of n distinct cities v1, v2, ..., vn that v1 = a, vn = b and there is a road between vi and vi + 1 for . On the other day, the similar thing happened. Limak wanted to travel between a city c and a city d. There is no road between them but there exists a sequence of n distinct cities u1, u2, ..., un that u1 = c, un = d and there is a road between ui and ui + 1 for .Also, Limak thinks that there are at most k roads in Bearland. He wonders whether he remembers everything correctly.Given n, k and four distinct cities a, b, c, d, can you find possible paths (v1, ..., vn) and (u1, ..., un) to satisfy all the given conditions? Find any solution or print -1 if it's impossible.",['graphs']625"Today, Yasser and Adel are at the shop buying cupcakes. There are $$$n$$$ cupcake types, arranged from $$$1$$$ to $$$n$$$ on the shelf, and there are infinitely many of each type. The tastiness of a cupcake of type $$$i$$$ is an integer $$$a_i$$$. There are both tasty and nasty cupcakes, so the tastiness can be positive, zero or negative.Yasser, of course, wants to try them all, so he will buy exactly one cupcake of each type.On the other hand, Adel will choose some segment $$$[l, r]$$$ $$$(1 \le l \le r \le n)$$$ that does not include all of cupcakes (he can't choose $$$[l, r] = [1, n]$$$) and buy exactly one cupcake of each of types $$$l, l + 1, \dots, r$$$.After that they will compare the total tastiness of the cupcakes each of them have bought. Yasser will be happy if the total tastiness of cupcakes he buys is strictly greater than the total tastiness of cupcakes Adel buys regardless of Adel's choice.For example, let the tastinesses of the cupcakes be $$$[7, 4, -1]$$$. Yasser will buy all of them, the total tastiness will be $$$7 + 4 - 1 = 10$$$. Adel can choose segments $$$[7], [4], [-1], [7, 4]$$$ or $$$[4, -1]$$$, their total tastinesses are $$$7, 4, -1, 11$$$ and $$$3$$$, respectively. Adel can choose segment with tastiness $$$11$$$, and as $$$10$$$ is not strictly greater than $$$11$$$, Yasser won't be happy :(Find out if Yasser will be happy after visiting the shop.",[]626"The employees of the F company have lots of ways to entertain themselves. Today they invited a famous magician who shows a trick with plastic cups and a marble.The point is to trick the spectator's attention. Initially, the spectator stands in front of a line of n plastic cups. Then the magician places a small marble under one cup and shuffles the cups. Then the spectator should guess which cup hides the marble.But the head coder of the F company isn't easy to trick. When he saw the performance, he noticed several important facts:  each cup contains a mark — a number from 1 to n; all marks on the cups are distinct;  the magician shuffles the cups in m operations, each operation looks like that: take a cup marked xi, sitting at position yi in the row of cups (the positions are numbered from left to right, starting from 1) and shift it to the very beginning of the cup row (on the first position). When the head coder came home after work he wanted to re-do the trick. Unfortunately, he didn't remember the starting or the final position of the cups. He only remembered which operations the magician performed. Help the coder: given the operations in the order they were made find at least one initial permutation of the cups that can go through the described operations in the given order. Otherwise, state that such permutation doesn't exist.",[]627"While sailing on a boat, Inessa noticed a beautiful water lily flower above the lake's surface. She came closer and it turned out that the lily was exactly $$$H$$$ centimeters above the water surface. Inessa grabbed the flower and sailed the distance of $$$L$$$ centimeters. Exactly at this point the flower touched the water surface.  Suppose that the lily grows at some point $$$A$$$ on the lake bottom, and its stem is always a straight segment with one endpoint at point $$$A$$$. Also suppose that initially the flower was exactly above the point $$$A$$$, i.e. its stem was vertical. Can you determine the depth of the lake at point $$$A$$$?","['math', 'geometry']"628"You like the card board game ""Set"". Each card contains $$$k$$$ features, each of which is equal to a value from the set $$$\{0, 1, 2\}$$$. The deck contains all possible variants of cards, that is, there are $$$3^k$$$ different cards in total.A feature for three cards is called good if it is the same for these cards or pairwise distinct. Three cards are called a set if all $$$k$$$ features are good for them.For example, the cards $$$(0, 0, 0)$$$, $$$(0, 2, 1)$$$, and $$$(0, 1, 2)$$$ form a set, but the cards $$$(0, 2, 2)$$$, $$$(2, 1, 2)$$$, and $$$(1, 2, 0)$$$ do not, as, for example, the last feature is not good.A group of five cards is called a meta-set, if there is strictly more than one set among them. How many meta-sets there are among given $$$n$$$ distinct cards?",['math']629"The Berland language consists of words having exactly two letters. Moreover, the first letter of a word is different from the second letter. Any combination of two different Berland letters (which, by the way, are the same as the lowercase letters of Latin alphabet) is a correct word in Berland language.The Berland dictionary contains all words of this language. The words are listed in a way they are usually ordered in dictionaries. Formally, word $$$a$$$ comes earlier than word $$$b$$$ in the dictionary if one of the following conditions hold:  the first letter of $$$a$$$ is less than the first letter of $$$b$$$;  the first letters of $$$a$$$ and $$$b$$$ are the same, and the second letter of $$$a$$$ is less than the second letter of $$$b$$$. So, the dictionary looks like that:  Word $$$1$$$: ab  Word $$$2$$$: ac  ...  Word $$$25$$$: az  Word $$$26$$$: ba  Word $$$27$$$: bc  ...  Word $$$649$$$: zx  Word $$$650$$$: zy You are given a word $$$s$$$ from the Berland language. Your task is to find its index in the dictionary.",['math']630"You are given an array $$$a$$$ of $$$n$$$ integers and a set $$$B$$$ of $$$m$$$ positive integers such that $$$1 \leq b_i \leq \lfloor \frac{n}{2} \rfloor$$$ for $$$1\le i\le m$$$, where $$$b_i$$$ is the $$$i$$$-th element of $$$B$$$. You can make the following operation on $$$a$$$:  Select some $$$x$$$ such that $$$x$$$ appears in $$$B$$$. Select an interval from array $$$a$$$ of size $$$x$$$ and multiply by $$$-1$$$ every element in the interval. Formally, select $$$l$$$ and $$$r$$$ such that $$$1\leq l\leq r \leq n$$$ and $$$r-l+1=x$$$, then assign $$$a_i:=-a_i$$$ for every $$$i$$$ such that $$$l\leq i\leq r$$$. Consider the following example, let $$$a=[0,6,-2,1,-4,5]$$$ and $$$B=\{1,2\}$$$:  $$$[0,6,-2,-1,4,5]$$$ is obtained after choosing size $$$2$$$ and $$$l=4$$$, $$$r=5$$$. $$$[0,6,2,-1,4,5]$$$ is obtained after choosing size $$$1$$$ and $$$l=3$$$, $$$r=3$$$. Find the maximum $$$\sum\limits_{i=1}^n {a_i}$$$ you can get after applying such operation any number of times (possibly zero).",['number theory']631"Alice has recently received an array $$$a_1, a_2, \dots, a_n$$$ for her birthday! She is very proud of her array, and when she showed her friend Bob the array, he was very happy with her present too!However, soon Bob became curious, and as any sane friend would do, asked Alice to perform $$$q$$$ operations of two types on her array:  $$$1$$$ $$$x$$$ $$$y$$$: update the element $$$a_x$$$ to $$$y$$$ (set $$$a_x = y$$$).  $$$2$$$ $$$l$$$ $$$r$$$: calculate how many non-decreasing subarrays exist within the subarray $$$[a_l, a_{l+1}, \dots, a_r]$$$. More formally, count the number of pairs of integers $$$(p,q)$$$ such that $$$l \le p \le q \le r$$$ and $$$a_p \le a_{p+1} \le \dots \le a_{q-1} \le a_q$$$. Help Alice answer Bob's queries!",['math']632"Shakespeare is a widely known esoteric programming language in which programs look like plays by Shakespeare, and numbers are given by combinations of ornate epithets. In this problem we will have a closer look at the way the numbers are described in Shakespeare.Each constant in Shakespeare is created from non-negative powers of 2 using arithmetic operations. For simplicity we'll allow only addition and subtraction and will look for a representation of the given number which requires a minimal number of operations.You are given an integer n. You have to represent it as n = a1 + a2 + ... + am, where each of ai is a non-negative power of 2, possibly multiplied by -1. Find a representation which minimizes the value of m.",[]633"Recently, Polycarp completed $$$n$$$ successive tasks.For each completed task, the time $$$s_i$$$ is known when it was given, no two tasks were given at the same time. Also given is the time $$$f_i$$$ when the task was completed. For each task, there is an unknown value $$$d_i$$$ ($$$d_i>0$$$) — duration of task execution.It is known that the tasks were completed in the order in which they came. Polycarp performed the tasks as follows:  As soon as the very first task came, Polycarp immediately began to carry it out.  If a new task arrived before Polycarp finished the previous one, he put the new task at the end of the queue.  When Polycarp finished executing the next task and the queue was not empty, he immediately took a new task from the head of the queue (if the queue is empty — he just waited for the next task). Find $$$d_i$$$ (duration) of each task.",[]634"Autumn came late to the kingdom of Far Far Away. The harvest was exuberant and it is now time to get ready for the winter. As most people celebrate the Harvest festival, Simon the Caretaker tries to solve a very non-trivial task of how to find place for the agricultural equipment in the warehouse.He's got problems with some particularly large piece of equipment, which is, of course, turboplows. The problem is that when a turboplow is stored, it takes up not some simply rectangular space. It takes up a T-shaped space like on one of the four pictures below (here character ""#"" stands for the space occupied by the turboplow and character ""."" stands for the free space):   ###      ..#      .#.      #...#.      ###      .#.      ###.#.      ..#      ###      #..   Simon faced a quite natural challenge: placing in the given n × m cells warehouse the maximum number of turboplows. As one stores the turboplows, he can rotate them in any manner (so that they take up the space like on one of the four pictures above). However, two turboplows cannot ""overlap"", that is, they cannot share the same cell in the warehouse.Simon feels that he alone cannot find the optimal way of positioning the plugs in the warehouse that would maximize their quantity. Can you help him?",[]635"Note that the memory limit is unusual.You are given a multiset consisting of $$$n$$$ integers. You have to process queries of two types:  add integer $$$k$$$ into the multiset;  find the $$$k$$$-th order statistics in the multiset and remove it. $$$k$$$-th order statistics in the multiset is the $$$k$$$-th element in the sorted list of all elements of the multiset. For example, if the multiset contains elements $$$1$$$, $$$4$$$, $$$2$$$, $$$1$$$, $$$4$$$, $$$5$$$, $$$7$$$, and $$$k = 3$$$, then you have to find the $$$3$$$-rd element in $$$[1, 1, 2, 4, 4, 5, 7]$$$, which is $$$2$$$. If you try to delete an element which occurs multiple times in the multiset, only one occurence is removed. After processing all queries, print any number belonging to the multiset, or say that it is empty.",[]636"You are a game designer and want to make an obstacle course. The player will walk from left to right. You have $$$n$$$ heights of mountains already selected and want to arrange them so that the absolute difference of the heights of the first and last mountains is as small as possible. In addition, you want to make the game difficult, and since walking uphill or flat is harder than walking downhill, the difficulty of the level will be the number of mountains $$$i$$$ ($$$1 \leq i < n$$$) such that $$$h_i \leq h_{i+1}$$$ where $$$h_i$$$ is the height of the $$$i$$$-th mountain. You don't want to waste any of the mountains you modelled, so you have to use all of them. From all the arrangements that minimize $$$|h_1-h_n|$$$, find one that is the most difficult. If there are multiple orders that satisfy these requirements, you may find any.",['math']637"This is the hard version of the problem. The difference between versions is the constraints on $$$n$$$ and $$$a_i$$$. You can make hacks only if all versions of the problem are solved.First, Aoi came up with the following idea for the competitive programming problem:Yuzu is a girl who collecting candies. Originally, she has $$$x$$$ candies. There are also $$$n$$$ enemies numbered with integers from $$$1$$$ to $$$n$$$. Enemy $$$i$$$ has $$$a_i$$$ candies.Yuzu is going to determine a permutation $$$P$$$. A permutation is an array consisting of $$$n$$$ distinct integers from $$$1$$$ to $$$n$$$ in arbitrary order. For example, $$$\{2,3,1,5,4\}$$$ is a permutation, but $$$\{1,2,2\}$$$ is not a permutation ($$$2$$$ appears twice in the array) and $$$\{1,3,4\}$$$ is also not a permutation (because $$$n=3$$$ but there is the number $$$4$$$ in the array).After that, she will do $$$n$$$ duels with the enemies with the following rules:  If Yuzu has equal or more number of candies than enemy $$$P_i$$$, she wins the duel and gets $$$1$$$ candy. Otherwise, she loses the duel and gets nothing.  The candy which Yuzu gets will be used in the next duels. Yuzu wants to win all duels. How many valid permutations $$$P$$$ exist?This problem was easy and wasn't interesting for Akari, who is a friend of Aoi. And Akari made the following problem from the above idea:Let's define $$$f(x)$$$ as the number of valid permutations for the integer $$$x$$$.You are given $$$n$$$, $$$a$$$ and a prime number $$$p \le n$$$. Let's call a positive integer $$$x$$$ good, if the value $$$f(x)$$$ is not divisible by $$$p$$$. Find all good integers $$$x$$$.Your task is to solve this problem made by Akari.","['math', 'number theory']"638"Each month Blake gets the report containing main economic indicators of the company ""Blake Technologies"". There are n commodities produced by the company. For each of them there is exactly one integer in the final report, that denotes corresponding revenue. Before the report gets to Blake, it passes through the hands of m managers. Each of them may reorder the elements in some order. Namely, the i-th manager either sorts first ri numbers in non-descending or non-ascending order and then passes the report to the manager i + 1, or directly to Blake (if this manager has number i = m).Employees of the ""Blake Technologies"" are preparing the report right now. You know the initial sequence ai of length n and the description of each manager, that is value ri and his favourite order. You are asked to speed up the process and determine how the final report will look like.",[]639"Twilight Sparkle was playing Ludo with her friends Rainbow Dash, Apple Jack and Flutter Shy. But she kept losing. Having returned to the castle, Twilight Sparkle became interested in the dice that were used in the game.The dice has m faces: the first face of the dice contains a dot, the second one contains two dots, and so on, the m-th face contains m dots. Twilight Sparkle is sure that when the dice is tossed, each face appears with probability . Also she knows that each toss is independent from others. Help her to calculate the expected maximum number of dots she could get after tossing the dice n times.",['probabilities']640"Given a sequence of integers a1, ..., an and q queries x1, ..., xq on it. For each query xi you have to count the number of pairs (l, r) such that 1 ≤ l ≤ r ≤ n and gcd(al, al + 1, ..., ar) = xi. is a greatest common divisor of v1, v2, ..., vn, that is equal to a largest positive integer that divides all vi.",['math']641"Crazy Town is a plane on which there are n infinite line roads. Each road is defined by the equation aix + biy + ci = 0, where ai and bi are not both equal to the zero. The roads divide the plane into connected regions, possibly of infinite space. Let's call each such region a block. We define an intersection as the point where at least two different roads intersect.Your home is located in one of the blocks. Today you need to get to the University, also located in some block. In one step you can move from one block to another, if the length of their common border is nonzero (in particular, this means that if the blocks are adjacent to one intersection, but have no shared nonzero boundary segment, then it are not allowed to move from one to another one in one step).Determine what is the minimum number of steps you have to perform to get to the block containing the university. It is guaranteed that neither your home nor the university is located on the road.","['math', 'geometry']"642"Kefa decided to celebrate his first big salary by going to the restaurant. He lives by an unusual park. The park is a rooted tree consisting of n vertices with the root at vertex 1. Vertex 1 also contains Kefa's house. Unfortunaely for our hero, the park also contains cats. Kefa has already found out what are the vertices with cats in them.The leaf vertices of the park contain restaurants. Kefa wants to choose a restaurant where he will go, but unfortunately he is very afraid of cats, so there is no way he will go to the restaurant if the path from the restaurant to his house contains more than m consecutive vertices with cats. Your task is to help Kefa count the number of restaurants where he can go.","['graphs', 'trees']"643"Linear Kingdom has exactly one tram line. It has n stops, numbered from 1 to n in the order of tram's movement. At the i-th stop ai passengers exit the tram, while bi passengers enter it. The tram is empty before it arrives at the first stop. Also, when the tram arrives at the last stop, all passengers exit so that it becomes empty.Your task is to calculate the tram's minimum capacity such that the number of people inside the tram at any time never exceeds this capacity. Note that at each stop all exiting passengers exit before any entering passenger enters the tram.",[]644"Let $$$s(x)$$$ be sum of digits in decimal representation of positive integer $$$x$$$. Given two integers $$$n$$$ and $$$m$$$, find some positive integers $$$a$$$ and $$$b$$$ such that   $$$s(a) \ge n$$$,  $$$s(b) \ge n$$$,  $$$s(a + b) \le m$$$. ",['math']645"You are given three points on a plane. You should choose some segments on the plane that are parallel to coordinate axes, so that all three points become connected. The total length of the chosen segments should be the minimal possible.Two points $$$a$$$ and $$$b$$$ are considered connected if there is a sequence of points $$$p_0 = a, p_1, \ldots, p_k = b$$$ such that points $$$p_i$$$ and $$$p_{i+1}$$$ lie on the same segment.",['geometry']646"This is an interactive problem.Vladik has favorite game, in which he plays all his free time.Game field could be represented as n × m matrix which consists of cells of three types:   «.» — normal cell, player can visit it.  «F» — finish cell, player has to finish his way there to win. There is exactly one cell of this type.  «*» — dangerous cell, if player comes to this cell, he loses. Initially player is located in the left top cell with coordinates (1, 1). Player has access to 4 buttons ""U"", ""D"", ""L"", ""R"", each of them move player up, down, left and right directions respectively.But it’s not that easy! Sometimes friends play game and change functions of buttons. Function of buttons ""L"" and ""R"" could have been swapped, also functions of buttons ""U"" and ""D"" could have been swapped. Note that functions of buttons can be changed only at the beginning of the game.Help Vladik win the game!",['graphs']647"You have a knapsack with the capacity of $$$W$$$. There are also $$$n$$$ items, the $$$i$$$-th one has weight $$$w_i$$$. You want to put some of these items into the knapsack in such a way that their total weight $$$C$$$ is at least half of its size, but (obviously) does not exceed it. Formally, $$$C$$$ should satisfy: $$$\lceil \frac{W}{2}\rceil \le C \le W$$$. Output the list of items you will put into the knapsack or determine that fulfilling the conditions is impossible. If there are several possible lists of items satisfying the conditions, you can output any. Note that you don't have to maximize the sum of weights of items in the knapsack.",['math']648"Zookeeper is playing a game. In this game, Zookeeper must use bombs to bomb a string that consists of letters 'A' and 'B'. He can use bombs to bomb a substring which is either ""AB"" or ""BB"". When he bombs such a substring, the substring gets deleted from the string and the remaining parts of the string get concatenated.For example, Zookeeper can use two such operations: AABABBA $$$\to$$$ AABBA $$$\to$$$ AAA.Zookeeper wonders what the shortest string he can make is. Can you help him find the length of the shortest string?",['strings']649"Unlike Knights of a Round Table, Knights of a Polygonal Table deprived of nobility and happy to kill each other. But each knight has some power and a knight can kill another knight if and only if his power is greater than the power of victim. However, even such a knight will torment his conscience, so he can kill no more than $$$k$$$ other knights. Also, each knight has some number of coins. After a kill, a knight can pick up all victim's coins.Now each knight ponders: how many coins he can have if only he kills other knights?You should answer this question for each knight.",[]650"There are $$$n$$$ points on the plane, $$$(x_1,y_1), (x_2,y_2), \ldots, (x_n,y_n)$$$.You need to place an isosceles triangle with two sides on the coordinate axis to cover all points (a point is covered if it lies inside the triangle or on the side of the triangle). Calculate the minimum length of the shorter side of the triangle.","['math', 'geometry']"651"Polycarp is very fond of playing the game Minesweeper. Recently he found a similar game and there are such rules.There are mines on the field, for each the coordinates of its location are known ($$$x_i, y_i$$$). Each mine has a lifetime in seconds, after which it will explode. After the explosion, the mine also detonates all mines vertically and horizontally at a distance of $$$k$$$ (two perpendicular lines). As a result, we get an explosion on the field in the form of a ""plus"" symbol ('+'). Thus, one explosion can cause new explosions, and so on.Also, Polycarp can detonate anyone mine every second, starting from zero seconds. After that, a chain reaction of explosions also takes place. Mines explode instantly and also instantly detonate other mines according to the rules described above.Polycarp wants to set a new record and asks you to help him calculate in what minimum number of seconds all mines can be detonated.",[]652"David was given a red checkered rectangle of size $$$n \times m$$$. But he doesn't like it. So David cuts the original or any other rectangle piece obtained during the cutting into two new pieces along the grid lines. He can do this operation as many times as he wants.As a result, he will get a set of rectangles. Rectangles $$$1 \times 1$$$ are forbidden.David also knows how to paint the cells blue. He wants each rectangle from the resulting set of pieces to be colored such that any pair of adjacent cells by side (from the same piece) have different colors.What is the minimum number of cells David will have to paint?",[]653"It's a beautiful April day and Wallace is playing football with his friends. But his friends do not know that Wallace actually stayed home with Gromit and sent them his robotic self instead. Robo-Wallace has several advantages over the other guys. For example, he can hit the ball directly to the specified point. And yet, the notion of a giveaway is foreign to him. The combination of these features makes the Robo-Wallace the perfect footballer — as soon as the ball gets to him, he can just aim and hit the goal. He followed this tactics in the first half of the match, but he hit the goal rarely. The opposing team has a very good goalkeeper who catches most of the balls that fly directly into the goal. But Robo-Wallace is a quick thinker, he realized that he can cheat the goalkeeper. After all, they are playing in a football box with solid walls. Robo-Wallace can kick the ball to the other side, then the goalkeeper will not try to catch the ball. Then, if the ball bounces off the wall and flies into the goal, the goal will at last be scored.Your task is to help Robo-Wallace to detect a spot on the wall of the football box, to which the robot should kick the ball, so that the ball bounces once and only once off this wall and goes straight to the goal. In the first half of the match Robo-Wallace got a ball in the head and was severely hit. As a result, some of the schemes have been damaged. Because of the damage, Robo-Wallace can only aim to his right wall (Robo-Wallace is standing with his face to the opposing team's goal).The football box is rectangular. Let's introduce a two-dimensional coordinate system so that point (0, 0) lies in the lower left corner of the field, if you look at the box above. Robo-Wallace is playing for the team, whose goal is to the right. It is an improvised football field, so the gate of Robo-Wallace's rivals may be not in the middle of the left wall.  In the given coordinate system you are given:   y1, y2 — the y-coordinates of the side pillars of the goalposts of robo-Wallace's opponents;  yw — the y-coordinate of the wall to which Robo-Wallace is aiming;  xb, yb — the coordinates of the ball's position when it is hit;  r — the radius of the ball. A goal is scored when the center of the ball crosses the OY axis in the given coordinate system between (0, y1) and (0, y2). The ball moves along a straight line. The ball's hit on the wall is perfectly elastic (the ball does not shrink from the hit), the angle of incidence equals the angle of reflection. If the ball bounces off the wall not to the goal, that is, if it hits the other wall or the goal post, then the opposing team catches the ball and Robo-Wallace starts looking for miscalculation and gets dysfunctional. Such an outcome, if possible, should be avoided. We assume that the ball touches an object, if the distance from the center of the ball to the object is no greater than the ball radius r.",['geometry']654"In one one-dimensional world there are n platforms. Platform with index k (platforms are numbered from 1) is a segment with coordinates [(k - 1)m, (k - 1)m + l], and l < m. Grasshopper Bob starts to jump along the platforms from point 0, with each jump he moves exactly d units right. Find out the coordinate of the point, where Bob will fall down. The grasshopper falls down, if he finds himself not on the platform, but if he finds himself on the edge of the platform, he doesn't fall down.",['math']655"Find out if it is possible to partition the first $$$n$$$ positive integers into two non-empty disjoint sets $$$S_1$$$ and $$$S_2$$$ such that:$$$\mathrm{gcd}(\mathrm{sum}(S_1), \mathrm{sum}(S_2)) > 1$$$ Here $$$\mathrm{sum}(S)$$$ denotes the sum of all elements present in set $$$S$$$ and $$$\mathrm{gcd}$$$ means thegreatest common divisor.Every integer number from $$$1$$$ to $$$n$$$ should be present in exactly one of $$$S_1$$$ or $$$S_2$$$.",['math']656"T is playing a game with his friend, HL.There are $$$n$$$ piles of stones, the $$$i$$$-th pile initially has $$$a_i$$$ stones. T and HL will take alternating turns, with T going first. In each turn, a player chooses a non-empty pile and then removes a single stone from it. However, one cannot choose a pile that has been chosen in the previous turn (the pile that was chosen by the other player, or if the current turn is the first turn then the player can choose any non-empty pile). The player who cannot choose a pile in his turn loses, and the game ends.Assuming both players play optimally, given the starting configuration of $$$t$$$ games, determine the winner of each game.",['games']657"One day Polycarpus stopped by a supermarket on his way home. It turns out that the supermarket is having a special offer for stools. The offer is as follows: if a customer's shopping cart contains at least one stool, the customer gets a 50% discount on the cheapest item in the cart (that is, it becomes two times cheaper). If there are several items with the same minimum price, the discount is available for only one of them!Polycarpus has k carts, and he wants to buy up all stools and pencils from the supermarket. Help him distribute the stools and the pencils among the shopping carts, so that the items' total price (including the discounts) is the least possible.Polycarpus must use all k carts to purchase the items, no shopping cart can remain empty. Each shopping cart can contain an arbitrary number of stools and/or pencils.",[]658"Vasya is a Greencode wildlife preservation society proponent. One day he found an empty field nobody owned, divided it into n × m squares and decided to plant a forest there. Vasya will plant nm trees of all different heights from 1 to nm. For his forest to look more natural he wants any two trees growing in the side neighbouring squares to have the absolute value of difference in heights to be strictly more than 1. Help Vasya: make the plan of the forest planting for which this condition is fulfilled.",[]659"Polycarp has just attempted to pass the driving test. He ran over the straight road with the signs of four types.  speed limit: this sign comes with a positive integer number — maximal speed of the car after the sign (cancel the action of the previous sign of this type);  overtake is allowed: this sign means that after some car meets it, it can overtake any other car;  no speed limit: this sign cancels speed limit if any (car can move with arbitrary speed after this sign);  no overtake allowed: some car can't overtake any other car after this sign. Polycarp goes past the signs consequentially, each new sign cancels the action of all the previous signs of it's kind (speed limit/overtake). It is possible that two or more ""no overtake allowed"" signs go one after another with zero ""overtake is allowed"" signs between them. It works with ""no speed limit"" and ""overtake is allowed"" signs as well.In the beginning of the ride overtake is allowed and there is no speed limit.You are given the sequence of events in chronological order — events which happened to Polycarp during the ride. There are events of following types:  Polycarp changes the speed of his car to specified (this event comes with a positive integer number);  Polycarp's car overtakes the other car;  Polycarp's car goes past the ""speed limit"" sign (this sign comes with a positive integer);  Polycarp's car goes past the ""overtake is allowed"" sign;  Polycarp's car goes past the ""no speed limit"";  Polycarp's car goes past the ""no overtake allowed""; It is guaranteed that the first event in chronological order is the event of type 1 (Polycarp changed the speed of his car to specified).After the exam Polycarp can justify his rule violations by telling the driving instructor that he just didn't notice some of the signs. What is the minimal number of signs Polycarp should say he didn't notice, so that he would make no rule violations from his point of view?",[]660"You are given a set of $$$2n+1$$$ integer points on a Cartesian plane. Points are numbered from $$$0$$$ to $$$2n$$$ inclusive. Let $$$P_i$$$ be the $$$i$$$-th point. The $$$x$$$-coordinate of the point $$$P_i$$$ equals $$$i$$$. The $$$y$$$-coordinate of the point $$$P_i$$$ equals zero (initially). Thus, initially $$$P_i=(i,0)$$$.The given points are vertices of a plot of a piecewise function. The $$$j$$$-th piece of the function is the segment $$$P_{j}P_{j + 1}$$$.In one move you can increase the $$$y$$$-coordinate of any point with odd $$$x$$$-coordinate (i.e. such points are $$$P_1, P_3, \dots, P_{2n-1}$$$) by $$$1$$$. Note that the corresponding segments also change.For example, the following plot shows a function for $$$n=3$$$ (i.e. number of points is $$$2\cdot3+1=7$$$) in which we increased the $$$y$$$-coordinate of the point $$$P_1$$$ three times and $$$y$$$-coordinate of the point $$$P_5$$$ one time:  Let the area of the plot be the area below this plot and above the coordinate axis OX. For example, the area of the plot on the picture above is 4 (the light blue area on the picture above is the area of the plot drawn on it).Let the height of the plot be the maximum $$$y$$$-coordinate among all initial points in the plot (i.e. points $$$P_0, P_1, \dots, P_{2n}$$$). The height of the plot on the picture above is 3.Your problem is to say which minimum possible height can have the plot consisting of $$$2n+1$$$ vertices and having an area equal to $$$k$$$. Note that it is unnecessary to minimize the number of moves.It is easy to see that any answer which can be obtained by performing moves described above always exists and is an integer number not exceeding $$$10^{18}$$$.",['math']661"Giant chess is quite common in Geraldion. We will not delve into the rules of the game, we'll just say that the game takes place on an h × w field, and it is painted in two colors, but not like in chess. Almost all cells of the field are white and only some of them are black. Currently Gerald is finishing a game of giant chess against his friend Pollard. Gerald has almost won, and the only thing he needs to win is to bring the pawn from the upper left corner of the board, where it is now standing, to the lower right corner. Gerald is so confident of victory that he became interested, in how many ways can he win?The pawn, which Gerald has got left can go in two ways: one cell down or one cell to the right. In addition, it can not go to the black cells, otherwise the Gerald still loses. There are no other pawns or pieces left on the field, so that, according to the rules of giant chess Gerald moves his pawn until the game is over, and Pollard is just watching this process.","['math', 'number theory']"662"A plane is flying at a constant height of $$$h$$$ meters above the ground surface. Let's consider that it is flying from the point $$$(-10^9, h)$$$ to the point $$$(10^9, h)$$$ parallel with $$$Ox$$$ axis.A glider is inside the plane, ready to start his flight at any moment (for the sake of simplicity let's consider that he may start only when the plane's coordinates are integers). After jumping from the plane, he will fly in the same direction as the plane, parallel to $$$Ox$$$ axis, covering a unit of distance every second. Naturally, he will also descend; thus his second coordinate will decrease by one unit every second.There are ascending air flows on certain segments, each such segment is characterized by two numbers $$$x_1$$$ and $$$x_2$$$ ($$$x_1 < x_2$$$) representing its endpoints. No two segments share any common points. When the glider is inside one of such segments, he doesn't descend, so his second coordinate stays the same each second. The glider still flies along $$$Ox$$$ axis, covering one unit of distance every second.     If the glider jumps out at $$$1$$$, he will stop at $$$10$$$. Otherwise, if he jumps out at $$$2$$$, he will stop at $$$12$$$. Determine the maximum distance along $$$Ox$$$ axis from the point where the glider's flight starts to the point where his flight ends if the glider can choose any integer coordinate to jump from the plane and start his flight. After touching the ground the glider stops altogether, so he cannot glide through an ascending airflow segment if his second coordinate is $$$0$$$.",[]663"Let us remind you part of the rules of Codeforces. The given rules slightly simplified, use the problem statement as a formal document.In the beginning of the round the contestants are divided into rooms. Each room contains exactly n participants. During the contest the participants are suggested to solve five problems, A, B, C, D and E. For each of these problem, depending on when the given problem was solved and whether it was solved at all, the participants receive some points. Besides, a contestant can perform hacks on other contestants. For each successful hack a contestant earns 100 points, for each unsuccessful hack a contestant loses 50 points. The number of points for every contestant is represented by the sum of points he has received from all his problems, including hacks.You are suggested to determine the leader for some room; the leader is a participant who has maximum points.",[]664"Permutation p is an ordered set of integers p1,  p2,  ...,  pn, consisting of n distinct positive integers, each of them doesn't exceed n. We'll denote the i-th element of permutation p as pi. We'll call number n the size or the length of permutation p1,  p2,  ...,  pn.You have a sequence of integers a1, a2, ..., an. In one move, you are allowed to decrease or increase any number by one. Count the minimum number of moves, needed to build a permutation from this sequence.",[]665"Petya loves lucky numbers. We all know that lucky numbers are the positive integers whose decimal representations contain only the lucky digits 4 and 7. For example, numbers 47, 744, 4 are lucky and 5, 17, 467 are not.Petya recently learned to determine whether a string of lowercase Latin letters is lucky. For each individual letter all its positions in the string are written out in the increasing order. This results in 26 lists of numbers; some of them can be empty. A string is considered lucky if and only if in each list the absolute difference of any two adjacent numbers is a lucky number. For example, let's consider string ""zbcdzefdzc"". The lists of positions of equal letters are: b: 2 c: 3, 10 d: 4, 8 e: 6 f: 7 z: 1, 5, 9 Lists of positions of letters a, g, h, ..., y are empty.This string is lucky as all differences are lucky numbers. For letters z: 5 - 1 = 4, 9 - 5 = 4, for letters c: 10 - 3 = 7, for letters d: 8 - 4 = 4. Note that if some letter occurs only once in a string, it doesn't influence the string's luckiness after building the lists of positions of equal letters. The string where all the letters are distinct is considered lucky.Find the lexicographically minimal lucky string whose length equals n.",['strings']666"For a given array $$$a$$$ consisting of $$$n$$$ integers and a given integer $$$m$$$ find if it is possible to reorder elements of the array $$$a$$$ in such a way that $$$\sum_{i=1}^{n}{\sum_{j=i}^{n}{\frac{a_j}{j}}}$$$ equals $$$m$$$? It is forbidden to delete elements as well as insert new elements. Please note that no rounding occurs during division, for example, $$$\frac{5}{2}=2.5$$$.",['math']667"This is the hard version of the problem. The difference between the versions is the constraint on $$$n$$$ and the required number of operations. You can make hacks only if all versions of the problem are solved.There are two binary strings $$$a$$$ and $$$b$$$ of length $$$n$$$ (a binary string is a string consisting of symbols $$$0$$$ and $$$1$$$). In an operation, you select a prefix of $$$a$$$, and simultaneously invert the bits in the prefix ($$$0$$$ changes to $$$1$$$ and $$$1$$$ changes to $$$0$$$) and reverse the order of the bits in the prefix.For example, if $$$a=001011$$$ and you select the prefix of length $$$3$$$, it becomes $$$011011$$$. Then if you select the entire string, it becomes $$$001001$$$.Your task is to transform the string $$$a$$$ into $$$b$$$ in at most $$$2n$$$ operations. It can be proved that it is always possible.",['strings']668"Throughout Igor K.'s life he has had many situations worthy of attention. We remember the story with the virus, the story of his mathematical career and of course, his famous programming achievements. However, one does not always adopt new hobbies, one can quit something as well.This time Igor K. got disappointed in one of his hobbies: editing and voicing videos. Moreover, he got disappointed in it so much, that he decided to destroy his secret archive for good. Igor K. use Pindows XR operation system which represents files and folders by small icons. At that, m icons can fit in a horizontal row in any window.Igor K.'s computer contains n folders in the D: disk's root catalog. The folders are numbered from 1 to n in the order from the left to the right and from top to bottom (see the images). At that the folders with secret videos have numbers from a to b inclusive. Igor K. wants to delete them forever, at that making as few frame selections as possible, and then pressing Shift+Delete exactly once. What is the minimum number of times Igor K. will have to select the folder in order to select folders from a to b and only them? Let us note that if some selected folder is selected repeatedly, then it is deselected. Each selection possesses the shape of some rectangle with sides parallel to the screen's borders.",[]669"Polycarp has $$$26$$$ tasks. Each task is designated by a capital letter of the Latin alphabet.The teacher asked Polycarp to solve tasks in the following way: if Polycarp began to solve some task, then he must solve it to the end, without being distracted by another task. After switching to another task, Polycarp cannot return to the previous task.Polycarp can only solve one task during the day. Every day he wrote down what task he solved. Now the teacher wants to know if Polycarp followed his advice.For example, if Polycarp solved tasks in the following order: ""DDBBCCCBBEZ"", then the teacher will see that on the third day Polycarp began to solve the task 'B', then on the fifth day he got distracted and began to solve the task 'C', on the eighth day Polycarp returned to the task 'B'. Other examples of when the teacher is suspicious: ""BAB"", ""AABBCCDDEEBZZ"" and ""AAAAZAAAAA"".If Polycarp solved the tasks as follows: ""FFGZZZY"", then the teacher cannot have any suspicions. Please note that Polycarp is not obligated to solve all tasks. Other examples of when the teacher doesn't have any suspicious: ""BA"", ""AFFFCC"" and ""YYYYY"".Help Polycarp find out if his teacher might be suspicious.",[]670"Vlad likes to eat in cafes very much. During his life, he has visited cafes n times. Unfortunately, Vlad started to feel that his last visits are not any different from each other. To fix that Vlad had a small research.First of all, Vlad assigned individual indices to all cafes. Then, he wrote down indices of cafes he visited in a row, in order of visiting them. Now, Vlad wants to find such a cafe that his last visit to that cafe was before his last visits to every other cafe. In other words, he wants to find such a cafe that he hasn't been there for as long as possible. Help Vlad to find that cafe.",[]671"This is the easy version of this problem. The only difference is the limit of $$$n$$$ - the length of the input string. In this version, $$$1 \leq n \leq 2000$$$. The hard version of this challenge is not offered in the round for the second division. Let's define a correct bracket sequence and its depth as follow:  An empty string is a correct bracket sequence with depth $$$0$$$.  If ""s"" is a correct bracket sequence with depth $$$d$$$ then ""(s)"" is a correct bracket sequence with depth $$$d + 1$$$.  If ""s"" and ""t"" are both correct bracket sequences then their concatenation ""st"" is a correct bracket sequence with depth equal to the maximum depth of $$$s$$$ and $$$t$$$. For a (not necessarily correct) bracket sequence $$$s$$$, we define its depth as the maximum depth of any correct bracket sequence induced by removing some characters from $$$s$$$ (possibly zero). For example: the bracket sequence $$$s = $$$""())(())"" has depth $$$2$$$, because by removing the third character we obtain a correct bracket sequence ""()(())"" with depth $$$2$$$.Given a string $$$a$$$ consists of only characters '(', ')' and '?'. Consider all (not necessarily correct) bracket sequences obtained by replacing all characters '?' in $$$a$$$ by either '(' or ')'. Calculate the sum of all the depths of all these bracket sequences. As this number can be large, find it modulo $$$998244353$$$.Hacks in this problem in the first division can be done only if easy and hard versions of this problem was solved.",['probabilities']672"There are three cells on an infinite 2-dimensional grid, labeled $$$A$$$, $$$B$$$, and $$$F$$$. Find the length of the shortest path from $$$A$$$ to $$$B$$$ if:   in one move you can go to any of the four adjacent cells sharing a side;  visiting the cell $$$F$$$ is forbidden (it is an obstacle). ",['math']673"You have a stripe of checkered paper of length $$$n$$$. Each cell is either white or black.What is the minimum number of cells that must be recolored from white to black in order to have a segment of $$$k$$$ consecutive black cells on the stripe?If the input data is such that a segment of $$$k$$$ consecutive black cells already exists, then print 0. ",[]674"Alice and Bob play a game. There is a paper strip which is divided into n + 1 cells numbered from left to right starting from 0. There is a chip placed in the n-th cell (the last one).Players take turns, Alice is first. Each player during his or her turn has to move the chip 1, 2 or k cells to the left (so, if the chip is currently in the cell i, the player can move it into cell i - 1, i - 2 or i - k). The chip should not leave the borders of the paper strip: it is impossible, for example, to move it k cells to the left if the current cell has number i < k. The player who can't make a move loses the game.Who wins if both participants play optimally?Alice and Bob would like to play several games, so you should determine the winner in each game.","['math', 'games']"675"Homer has two friends Alice and Bob. Both of them are string fans. One day, Alice and Bob decide to play a game on a string $$$s = s_1 s_2 \dots s_n$$$ of length $$$n$$$ consisting of lowercase English letters. They move in turns alternatively and Alice makes the first move.In a move, a player must choose an index $$$i$$$ ($$$1 \leq i \leq n$$$) that has not been chosen before, and change $$$s_i$$$ to any other lowercase English letter $$$c$$$ that $$$c \neq s_i$$$.When all indices have been chosen, the game ends. The goal of Alice is to make the final string lexicographically as small as possible, while the goal of Bob is to make the final string lexicographically as large as possible. Both of them are game experts, so they always play games optimally. Homer is not a game expert, so he wonders what the final string will be.A string $$$a$$$ is lexicographically smaller than a string $$$b$$$ if and only if one of the following holds:   $$$a$$$ is a prefix of $$$b$$$, but $$$a \ne b$$$;  in the first position where $$$a$$$ and $$$b$$$ differ, the string $$$a$$$ has a letter that appears earlier in the alphabet than the corresponding letter in $$$b$$$. ","['strings', 'games']"676"You are given $$$n$$$ patterns $$$p_1, p_2, \dots, p_n$$$ and $$$m$$$ strings $$$s_1, s_2, \dots, s_m$$$. Each pattern $$$p_i$$$ consists of $$$k$$$ characters that are either lowercase Latin letters or wildcard characters (denoted by underscores). All patterns are pairwise distinct. Each string $$$s_j$$$ consists of $$$k$$$ lowercase Latin letters.A string $$$a$$$ matches a pattern $$$b$$$ if for each $$$i$$$ from $$$1$$$ to $$$k$$$ either $$$b_i$$$ is a wildcard character or $$$b_i=a_i$$$.You are asked to rearrange the patterns in such a way that the first pattern the $$$j$$$-th string matches is $$$p[mt_j]$$$. You are allowed to leave the order of the patterns unchanged.Can you perform such a rearrangement? If you can, then print any valid order.","['graphs', 'strings']"677"You are given a tree consisting of $$$n$$$ vertices. A tree is an undirected connected acyclic graph.    Example of a tree. You have to paint each vertex into one of three colors. For each vertex, you know the cost of painting it in every color.You have to paint the vertices so that any path consisting of exactly three distinct vertices does not contain any vertices with equal colors. In other words, let's consider all triples $$$(x, y, z)$$$ such that $$$x \neq y, y \neq z, x \neq z$$$, $$$x$$$ is connected by an edge with $$$y$$$, and $$$y$$$ is connected by an edge with $$$z$$$. The colours of $$$x$$$, $$$y$$$ and $$$z$$$ should be pairwise distinct. Let's call a painting which meets this condition good.You have to calculate the minimum cost of a good painting and find one of the optimal paintings. If there is no good painting, report about it.","['graphs', 'trees']"678"Consider a sequence [a1, a2, ... , an]. Define its prefix product sequence .Now given n, find a permutation of [1, 2, ..., n], such that its prefix product sequence is a permutation of [0, 1, ..., n - 1].","['math', 'number theory']"679"A star is a figure of the following type: an asterisk character '*' in the center of the figure and four rays (to the left, right, top, bottom) of the same positive length. The size of a star is the length of its rays. The size of a star must be a positive number (i.e. rays of length $$$0$$$ are not allowed).Let's consider empty cells are denoted by '.', then the following figures are stars:  The leftmost figure is a star of size $$$1$$$, the middle figure is a star of size $$$2$$$ and the rightmost figure is a star of size $$$3$$$. You are given a rectangular grid of size $$$n \times m$$$ consisting only of asterisks '*' and periods (dots) '.'. Rows are numbered from $$$1$$$ to $$$n$$$, columns are numbered from $$$1$$$ to $$$m$$$. Your task is to draw this grid using any number of stars or find out that it is impossible. Stars can intersect, overlap or even coincide with each other. The number of stars in the output can't exceed $$$n \cdot m$$$. Each star should be completely inside the grid. You can use stars of same and arbitrary sizes.In this problem, you do not need to minimize the number of stars. Just find any way to draw the given grid with at most $$$n \cdot m$$$ stars.",[]680"BerOilGasDiamondBank has branches in n cities, at that n is an even number. The bank management wants to publish a calendar with the names of all those cities written in two columns: the calendar should consist of exactly n / 2 lines of strictly equal length, each of which contains exactly two names and exactly one separator character between them. The name of every city should be used in the calendar exactly once. For historical reasons the symbol d is used as the separator of words in the calendar. The BerOilGasDiamondBank management wants to show that all its branches are equally important to it, that's why the order of their appearance in the calendar should be following: if we ""glue""(concatinate) all the n / 2 calendar lines (from top to bottom) to make a single line, then the lexicographically minimal line is obtained. No separator character will be used to separate calendar lines. For example, if the lines are ""bertown!berville"", ""newberville!bera"", then the resulting line is ""bertown!bervillenewberville!bera"". In some sense one has to find the lexicographically minimal calendar, where the comparison of calendars happens line by line.Help BerOilGasDiamondBank and construct the required calendar.",['strings']681"In a small restaurant there are a tables for one person and b tables for two persons. It it known that n groups of people come today, each consisting of one or two people. If a group consist of one person, it is seated at a vacant one-seater table. If there are none of them, it is seated at a vacant two-seater table. If there are none of them, it is seated at a two-seater table occupied by single person. If there are still none of them, the restaurant denies service to this group.If a group consist of two people, it is seated at a vacant two-seater table. If there are none of them, the restaurant denies service to this group.You are given a chronological order of groups coming. You are to determine the total number of people the restaurant denies service to.",[]682"It's been almost a week since Polycarp couldn't get rid of insomnia. And as you may already know, one week in Berland lasts k days!When Polycarp went to a doctor with his problem, the doctor asked him about his sleeping schedule (more specifically, the average amount of hours of sleep per week). Luckily, Polycarp kept records of sleep times for the last n days. So now he has a sequence a1, a2, ..., an, where ai is the sleep time on the i-th day.The number of records is so large that Polycarp is unable to calculate the average value by himself. Thus he is asking you to help him with the calculations. To get the average Polycarp is going to consider k consecutive days as a week. So there will be n - k + 1 weeks to take into consideration. For example, if k = 2, n = 3 and a = [3, 4, 7], then the result is .You should write a program which will calculate average sleep times of Polycarp over all weeks.",['math']683"You a captain of a ship. Initially you are standing in a point $$$(x_1, y_1)$$$ (obviously, all positions in the sea can be described by cartesian plane) and you want to travel to a point $$$(x_2, y_2)$$$. You know the weather forecast — the string $$$s$$$ of length $$$n$$$, consisting only of letters U, D, L and R. The letter corresponds to a direction of wind. Moreover, the forecast is periodic, e.g. the first day wind blows to the side $$$s_1$$$, the second day — $$$s_2$$$, the $$$n$$$-th day — $$$s_n$$$ and $$$(n+1)$$$-th day — $$$s_1$$$ again and so on. Ship coordinates change the following way:  if wind blows the direction U, then the ship moves from $$$(x, y)$$$ to $$$(x, y + 1)$$$;  if wind blows the direction D, then the ship moves from $$$(x, y)$$$ to $$$(x, y - 1)$$$;  if wind blows the direction L, then the ship moves from $$$(x, y)$$$ to $$$(x - 1, y)$$$;  if wind blows the direction R, then the ship moves from $$$(x, y)$$$ to $$$(x + 1, y)$$$. The ship can also either go one of the four directions or stay in place each day. If it goes then it's exactly 1 unit of distance. Transpositions of the ship and the wind add up. If the ship stays in place, then only the direction of wind counts. For example, if wind blows the direction U and the ship moves the direction L, then from point $$$(x, y)$$$ it will move to the point $$$(x - 1, y + 1)$$$, and if it goes the direction U, then it will move to the point $$$(x, y + 2)$$$.You task is to determine the minimal number of days required for the ship to reach the point $$$(x_2, y_2)$$$.",[]684"You are given a binary matrix $$$A$$$ of size $$$n \times n$$$. Rows are numbered from top to bottom from $$$1$$$ to $$$n$$$, columns are numbered from left to right from $$$1$$$ to $$$n$$$. The element located at the intersection of row $$$i$$$ and column $$$j$$$ is called $$$A_{ij}$$$. Consider a set of $$$4$$$ operations:  Cyclically shift all rows up. The row with index $$$i$$$ will be written in place of the row $$$i-1$$$ ($$$2 \le i \le n$$$), the row with index $$$1$$$ will be written in place of the row $$$n$$$.  Cyclically shift all rows down. The row with index $$$i$$$ will be written in place of the row $$$i+1$$$ ($$$1 \le i \le n - 1$$$), the row with index $$$n$$$ will be written in place of the row $$$1$$$.  Cyclically shift all columns to the left. The column with index $$$j$$$ will be written in place of the column $$$j-1$$$ ($$$2 \le j \le n$$$), the column with index $$$1$$$ will be written in place of the column $$$n$$$.  Cyclically shift all columns to the right. The column with index $$$j$$$ will be written in place of the column $$$j+1$$$ ($$$1 \le j \le n - 1$$$), the column with index $$$n$$$ will be written in place of the column $$$1$$$.     The $$$3 \times 3$$$ matrix is shown on the left before the $$$3$$$-rd operation is applied to it, on the right — after. You can perform an arbitrary (possibly zero) number of operations on the matrix; the operations can be performed in any order.After that, you can perform an arbitrary (possibly zero) number of new xor-operations:  Select any element $$$A_{ij}$$$ and assign it with new value $$$A_{ij} \oplus 1$$$. In other words, the value of $$$(A_{ij} + 1) \bmod 2$$$ will have to be written into element $$$A_{ij}$$$. Each application of this xor-operation costs one burl. Note that the $$$4$$$ shift operations — are free. These $$$4$$$ operations can only be performed before xor-operations are performed.Output the minimum number of burles you would have to pay to make the $$$A$$$ matrix unitary. A unitary matrix is a matrix with ones on the main diagonal and the rest of its elements are zeros (that is, $$$A_{ij} = 1$$$ if $$$i = j$$$ and $$$A_{ij} = 0$$$ otherwise).",[]685"Sereja has a bracket sequence s1, s2, ..., sn, or, in other words, a string s of length n, consisting of characters ""("" and "")"".Sereja needs to answer m queries, each of them is described by two integers li, ri (1 ≤ li ≤ ri ≤ n). The answer to the i-th query is the length of the maximum correct bracket subsequence of sequence sli, sli + 1, ..., sri. Help Sereja answer all queries.You can find the definitions for a subsequence and a correct bracket sequence in the notes.",[]686"Gregor is learning about RSA cryptography, and although he doesn't understand how RSA works, he is now fascinated with prime numbers and factoring them.Gregor's favorite prime number is $$$P$$$. Gregor wants to find two bases of $$$P$$$. Formally, Gregor is looking for two integers $$$a$$$ and $$$b$$$ which satisfy both of the following properties.  $$$P \bmod a = P \bmod b$$$, where $$$x \bmod y$$$ denotes the remainder when $$$x$$$ is divided by $$$y$$$, and  $$$2 \le a < b \le P$$$. Help Gregor find two bases of his favorite prime number!","['math', 'number theory']"687"You are given a positive decimal number x.Your task is to convert it to the ""simple exponential notation"".Let x = a·10b, where 1 ≤ a < 10, then in general case the ""simple exponential notation"" looks like ""aEb"". If b equals to zero, the part ""Eb"" should be skipped. If a is an integer, it should be written without decimal point. Also there should not be extra zeroes in a and b.",['strings']688"Welcome to Innopolis city. Throughout the whole year, Innopolis citizens suffer from everlasting city construction. From the window in your room, you see the sequence of n hills, where i-th of them has height ai. The Innopolis administration wants to build some houses on the hills. However, for the sake of city appearance, a house can be only built on the hill, which is strictly higher than neighbouring hills (if they are present). For example, if the sequence of heights is 5, 4, 6, 2, then houses could be built on hills with heights 5 and 6 only.The Innopolis administration has an excavator, that can decrease the height of an arbitrary hill by one in one hour. The excavator can only work on one hill at a time. It is allowed to decrease hills up to zero height, or even to negative values. Increasing height of any hill is impossible. The city administration wants to build k houses, so there must be at least k hills that satisfy the condition above. What is the minimum time required to adjust the hills to achieve the administration's plan?However, the exact value of k is not yet determined, so could you please calculate answers for all k in range ? Here  denotes n divided by two, rounded up.",[]689"A car number in Berland consists of exactly n digits. A number is called beautiful if it has at least k equal digits. Vasya wants to change the digits in his car's number so that the number became beautiful. To replace one of n digits Vasya has to pay the sum of money, equal to the absolute difference between the old digit and the new one.Help Vasya: find the minimum sum of money he should pay to make the number of his car beautiful. You should also find the resulting beautiful number. If there are several such numbers, then print the lexicographically minimum one.",['strings']690"Since Sonya has just learned the basics of matrices, she decided to play with them a little bit.Sonya imagined a new type of matrices that she called rhombic matrices. These matrices have exactly one zero, while all other cells have the Manhattan distance to the cell containing the zero. The cells with equal numbers have the form of a rhombus, that is why Sonya called this type so.The Manhattan distance between two cells ($$$x_1$$$, $$$y_1$$$) and ($$$x_2$$$, $$$y_2$$$) is defined as $$$|x_1 - x_2| + |y_1 - y_2|$$$. For example, the Manhattan distance between the cells $$$(5, 2)$$$ and $$$(7, 1)$$$ equals to $$$|5-7|+|2-1|=3$$$.    Example of a rhombic matrix. Note that rhombic matrices are uniquely defined by $$$n$$$, $$$m$$$, and the coordinates of the cell containing the zero.She drew a $$$n\times m$$$ rhombic matrix. She believes that you can not recreate the matrix if she gives you only the elements of this matrix in some arbitrary order (i.e., the sequence of $$$n\cdot m$$$ numbers). Note that Sonya will not give you $$$n$$$ and $$$m$$$, so only the sequence of numbers in this matrix will be at your disposal.Write a program that finds such an $$$n\times m$$$ rhombic matrix whose elements are the same as the elements in the sequence in some order.",[]691"On a history lesson the teacher asked Vasya to name the dates when n famous events took place. He doesn't remembers the exact dates but he remembers a segment of days [li, ri] (inclusive) on which the event could have taken place. However Vasya also remembers that there was at most one event in one day. Help him choose such n dates of famous events that will fulfill both conditions. It is guaranteed that it is possible.",[]692"You are given a convex polygon P with n distinct vertices p1, p2, ..., pn. Vertex pi has coordinates (xi, yi) in the 2D plane. These vertices are listed in clockwise order.You can choose a real number D and move each vertex of the polygon a distance of at most D from their original positions.Find the maximum value of D such that no matter how you move the vertices, the polygon does not intersect itself and stays convex.",['geometry']693"And where the are the phone numbers?You are given a string s consisting of lowercase English letters and an integer k. Find the lexicographically smallest string t of length k, such that its set of letters is a subset of the set of letters of s and s is lexicographically smaller than t.It's guaranteed that the answer exists.Note that the set of letters is a set, not a multiset. For example, the set of letters of abadaba is {a, b, d}.String p is lexicographically smaller than string q, if p is a prefix of q, is not equal to q or there exists i, such that pi < qi and for all j < i it is satisfied that pj = qj. For example, abc is lexicographically smaller than abcd , abd is lexicographically smaller than abec, afa is not lexicographically smaller than ab and a is not lexicographically smaller than a.",['strings']694"Valera loves his garden, where n fruit trees grow.This year he will enjoy a great harvest! On the i-th tree bi fruit grow, they will ripen on a day number ai. Unfortunately, the fruit on the tree get withered, so they can only be collected on day ai and day ai + 1 (all fruits that are not collected in these two days, become unfit to eat).Valera is not very fast, but there are some positive points. Valera is ready to work every day. In one day, Valera can collect no more than v fruits. The fruits may be either from the same tree, or from different ones. What is the maximum amount of fruit Valera can collect for all time, if he operates optimally well?",[]695"You are given an array $$$a$$$ of length $$$n$$$. The array is called 3SUM-closed if for all distinct indices $$$i$$$, $$$j$$$, $$$k$$$, the sum $$$a_i + a_j + a_k$$$ is an element of the array. More formally, $$$a$$$ is 3SUM-closed if for all integers $$$1 \leq i < j < k \leq n$$$, there exists some integer $$$1 \leq l \leq n$$$ such that $$$a_i + a_j + a_k = a_l$$$.Determine if $$$a$$$ is 3SUM-closed.",[]696"While Mahmoud and Ehab were practicing for IOI, they found a problem which name was Longest common subsequence. They solved it, and then Ehab challenged Mahmoud with another problem.Given two strings a and b, find the length of their longest uncommon subsequence, which is the longest string that is a subsequence of one of them and not a subsequence of the other.A subsequence of some string is a sequence of characters that appears in the same order in the string, The appearances don't have to be consecutive, for example, strings ""ac"", ""bc"", ""abc"" and ""a"" are subsequences of string ""abc"" while strings ""abbc"" and ""acb"" are not. The empty string is a subsequence of any string. Any string is a subsequence of itself.",['strings']697"Vasya used to be an accountant before the war began and he is one of the few who knows how to operate a computer, so he was assigned as the programmer.We all know that programs often store sets of integers. For example, if we have a problem about a weighted directed graph, its edge can be represented by three integers: the number of the starting vertex, the number of the final vertex and the edge's weight. So, as Vasya was trying to represent characteristics of a recently invented robot in his program, he faced the following problem.Vasya is not a programmer, so he asked his friend Gena, what the convenient way to store n integers is. Gena used to code in language X-- and so he can use only the types that occur in this language. Let's define, what a ""type"" is in language X--:  First, a type is a string ""int"".  Second, a type is a string that starts with ""pair"", then followed by angle brackets listing exactly two comma-separated other types of language X--. This record contains no spaces.  No other strings can be regarded as types. More formally: type := int | pair<type,type>. For example, Gena uses the following type for graph edges: pair<int,pair<int,int>>.Gena was pleased to help Vasya, he dictated to Vasya a type of language X--, that stores n integers. Unfortunately, Gena was in a hurry, so he omitted the punctuation. Now Gena has already left and Vasya can't find the correct punctuation, resulting in a type of language X--, however hard he tries.Help Vasya and add the punctuation marks so as to receive the valid type of language X--. Otherwise say that the task is impossible to perform.",[]698"The only difference between easy and hard versions is constraints.The BerTV channel every day broadcasts one episode of one of the $$$k$$$ TV shows. You know the schedule for the next $$$n$$$ days: a sequence of integers $$$a_1, a_2, \dots, a_n$$$ ($$$1 \le a_i \le k$$$), where $$$a_i$$$ is the show, the episode of which will be shown in $$$i$$$-th day.The subscription to the show is bought for the entire show (i.e. for all its episodes), for each show the subscription is bought separately.How many minimum subscriptions do you need to buy in order to have the opportunity to watch episodes of purchased shows $$$d$$$ ($$$1 \le d \le n$$$) days in a row? In other words, you want to buy the minimum number of TV shows so that there is some segment of $$$d$$$ consecutive days in which all episodes belong to the purchased shows.",[]699"Alyona has recently bought a miniature fridge that can be represented as a matrix with $$$h$$$ rows and $$$2$$$ columns. Initially there is only one shelf at the bottom of the fridge, but Alyona can install arbitrary number of shelves inside the fridge between any two rows. A shelf is two cells wide, does not occupy any space but separates the inside of the fridge to the lower and upper part.  An example of a fridge with $$$h = 7$$$ and two shelves. The shelves are shown in black. The picture corresponds to the first example. Alyona has $$$n$$$ bottles of milk that she wants to put in the fridge. The $$$i$$$-th bottle is $$$a_i$$$ cells tall and $$$1$$$ cell wide. She can put a bottle on some shelf if the corresponding space above the shelf is at least as tall as the bottle. She can not put a bottle on top of another bottle (if there is no shelf between them). Two bottles can not share a cell.Alyona is interested in the largest integer $$$k$$$ such that she can put bottles $$$1$$$, $$$2$$$, ..., $$$k$$$ in the fridge at the same time. Find this largest $$$k$$$.",[]700"During the research on properties of the greatest common divisor (GCD) of a set of numbers, Ildar, a famous mathematician, introduced a brand new concept of the weakened common divisor (WCD) of a list of pairs of integers.For a given list of pairs of integers $$$(a_1, b_1)$$$, $$$(a_2, b_2)$$$, ..., $$$(a_n, b_n)$$$ their WCD is arbitrary integer greater than $$$1$$$, such that it divides at least one element in each pair. WCD may not exist for some lists.For example, if the list looks like $$$[(12, 15), (25, 18), (10, 24)]$$$, then their WCD can be equal to $$$2$$$, $$$3$$$, $$$5$$$ or $$$6$$$ (each of these numbers is strictly greater than $$$1$$$ and divides at least one number in each pair).You're currently pursuing your PhD degree under Ildar's mentorship, and that's why this problem was delegated to you. Your task is to calculate WCD efficiently.",['number theory']701"You are storing an integer array of length $$$m$$$ in a database. To maintain internal integrity and protect data, the database stores $$$n$$$ copies of this array.Unfortunately, the recent incident may have altered the stored information in every copy in the database.It's believed, that the incident altered at most two elements in every copy. You need to recover the original array based on the current state of the database.In case there are multiple ways to restore the array, report any. If there is no array that differs from every copy in no more than two positions, report that as well.",[]702"You are given three integers $$$a$$$, $$$b$$$, $$$k$$$.Find two binary integers $$$x$$$ and $$$y$$$ ($$$x \ge y$$$) such that   both $$$x$$$ and $$$y$$$ consist of $$$a$$$ zeroes and $$$b$$$ ones;  $$$x - y$$$ (also written in binary form) has exactly $$$k$$$ ones.  You are not allowed to use leading zeros for $$$x$$$ and $$$y$$$. ",['math']703"Codeforces user' handle color depends on his rating — it is red if his rating is greater or equal to 2400; it is orange if his rating is less than 2400 but greater or equal to 2200, etc. Each time participant takes part in a rated contest, his rating is changed depending on his performance.Anton wants the color of his handle to become red. He considers his performance in the rated contest to be good if he outscored some participant, whose handle was colored red before the contest and his rating has increased after it.Anton has written a program that analyses contest results and determines whether he performed good or not. Are you able to do the same?",[]704"Monocarp is playing a computer game. In this game, his character fights different monsters.A fight between a character and a monster goes as follows. Suppose the character initially has health $$$h_C$$$ and attack $$$d_C$$$; the monster initially has health $$$h_M$$$ and attack $$$d_M$$$. The fight consists of several steps:  the character attacks the monster, decreasing the monster's health by $$$d_C$$$;  the monster attacks the character, decreasing the character's health by $$$d_M$$$;  the character attacks the monster, decreasing the monster's health by $$$d_C$$$;  the monster attacks the character, decreasing the character's health by $$$d_M$$$;  and so on, until the end of the fight. The fight ends when someone's health becomes non-positive (i. e. $$$0$$$ or less). If the monster's health becomes non-positive, the character wins, otherwise the monster wins.Monocarp's character currently has health equal to $$$h_C$$$ and attack equal to $$$d_C$$$. He wants to slay a monster with health equal to $$$h_M$$$ and attack equal to $$$d_M$$$. Before the fight, Monocarp can spend up to $$$k$$$ coins to upgrade his character's weapon and/or armor; each upgrade costs exactly one coin, each weapon upgrade increases the character's attack by $$$w$$$, and each armor upgrade increases the character's health by $$$a$$$.Can Monocarp's character slay the monster if Monocarp spends coins on upgrades optimally?",['math']705"Little Susie listens to fairy tales before bed every day. Today's fairy tale was about wood cutters and the little girl immediately started imagining the choppers cutting wood. She imagined the situation that is described below.There are n trees located along the road at points with coordinates x1, x2, ..., xn. Each tree has its height hi. Woodcutters can cut down a tree and fell it to the left or to the right. After that it occupies one of the segments [xi - hi, xi] or [xi;xi + hi]. The tree that is not cut down occupies a single point with coordinate xi. Woodcutters can fell a tree if the segment to be occupied by the fallen tree doesn't contain any occupied point. The woodcutters want to process as many trees as possible, so Susie wonders, what is the maximum number of trees to fell. ",[]706"  Before becoming a successful trader William got a university degree. During his education an interesting situation happened, after which William started to listen to homework assignments much more attentively. What follows is the correct formal description of the homework assignment:You are given a string $$$s$$$ of length $$$n$$$ only consisting of characters ""a"", ""b"" and ""c"". There are $$$q$$$ queries of format ($$$pos, c$$$), meaning replacing the element of string $$$s$$$ at position $$$pos$$$ with character $$$c$$$. After each query you must output the minimal number of characters in the string, which have to be replaced, so that the string doesn't contain string ""abc"" as a substring. A valid replacement of a character is replacing it with ""a"", ""b"" or ""c"".A string $$$x$$$ is a substring of a string $$$y$$$ if $$$x$$$ can be obtained from $$$y$$$ by deletion of several (possibly, zero or all) characters from the beginning and several (possibly, zero or all) characters from the end.",['strings']707"The marmots need to prepare k problems for HC2 over n days. Each problem, once prepared, also has to be printed.The preparation of a problem on day i (at most one per day) costs ai CHF, and the printing of a problem on day i (also at most one per day) costs bi CHF. Of course, a problem cannot be printed before it has been prepared (but doing both on the same day is fine).What is the minimum cost of preparation and printing?",['graphs']708"Given an undirected connected graph with $$$n$$$ vertices and $$$m$$$ edges. The graph contains no loops (edges from a vertex to itself) and multiple edges (i.e. no more than one edge between each pair of vertices). The vertices of the graph are numbered from $$$1$$$ to $$$n$$$. Find the number of paths from a vertex $$$s$$$ to $$$t$$$ whose length differs from the shortest path from $$$s$$$ to $$$t$$$ by no more than $$$1$$$. It is necessary to consider all suitable paths, even if they pass through the same vertex or edge more than once (i.e. they are not simple).    Graph consisting of $$$6$$$ of vertices and $$$8$$$ of edges For example, let $$$n = 6$$$, $$$m = 8$$$, $$$s = 6$$$ and $$$t = 1$$$, and let the graph look like the figure above. Then the length of the shortest path from $$$s$$$ to $$$t$$$ is $$$1$$$. Consider all paths whose length is at most $$$1 + 1 = 2$$$.   $$$6 \rightarrow 1$$$. The length of the path is $$$1$$$.  $$$6 \rightarrow 4 \rightarrow 1$$$. Path length is $$$2$$$.  $$$6 \rightarrow 2 \rightarrow 1$$$. Path length is $$$2$$$.  $$$6 \rightarrow 5 \rightarrow 1$$$. Path length is $$$2$$$. There is a total of $$$4$$$ of matching paths.",['graphs']709"Little Janet likes playing with cubes. Actually, she likes to play with anything whatsoever, cubes or tesseracts, as long as they are multicolored. Each cube is described by two parameters — color ci and size si. A Zebra Tower is a tower that consists of cubes of exactly two colors. Besides, the colors of the cubes in the tower must alternate (colors of adjacent cubes must differ). The Zebra Tower should have at least two cubes. There are no other limitations. The figure below shows an example of a Zebra Tower.  A Zebra Tower's height is the sum of sizes of all cubes that form the tower. Help little Janet build the Zebra Tower of the maximum possible height, using the available cubes.",[]710"You are given an array of n elements, you must make it a co-prime array in as few moves as possible.In each move you can insert any positive integral number you want not greater than 109 in any place in the array.An array is co-prime if any two adjacent numbers of it are co-prime.In the number theory, two integers a and b are said to be co-prime if the only positive integer that divides both of them is 1.","['math', 'number theory']"711"You are given an array $$$a[0 \ldots n - 1] = [a_0, a_1, \ldots, a_{n - 1}]$$$ of zeroes and ones only. Note that in this problem, unlike the others, the array indexes are numbered from zero, not from one.In one step, the array $$$a$$$ is replaced by another array of length $$$n$$$ according to the following rules:   First, a new array $$$a^{\rightarrow d}$$$ is defined as a cyclic shift of the array $$$a$$$ to the right by $$$d$$$ cells. The elements of this array can be defined as $$$a^{\rightarrow d}_i = a_{(i + n - d) \bmod n}$$$, where $$$(i + n - d) \bmod n$$$ is the remainder of integer division of $$$i + n - d$$$ by $$$n$$$.  It means that the whole array $$$a^{\rightarrow d}$$$ can be represented as a sequence $$$$$$a^{\rightarrow d} = [a_{n - d}, a_{n - d + 1}, \ldots, a_{n - 1}, a_0, a_1, \ldots, a_{n - d - 1}]$$$$$$  Then each element of the array $$$a_i$$$ is replaced by $$$a_i \,\&\, a^{\rightarrow d}_i$$$, where $$$\&$$$ is a logical ""AND"" operator. For example, if $$$a = [0, 0, 1, 1]$$$ and $$$d = 1$$$, then $$$a^{\rightarrow d} = [1, 0, 0, 1]$$$ and the value of $$$a$$$ after the first step will be $$$[0 \,\&\, 1, 0 \,\&\, 0, 1 \,\&\, 0, 1 \,\&\, 1]$$$, that is $$$[0, 0, 0, 1]$$$.The process ends when the array stops changing. For a given array $$$a$$$, determine whether it will consist of only zeros at the end of the process. If yes, also find the number of steps the process will take before it finishes.","['math', 'graphs', 'number theory']"712"Vasya plays the Geometry Horse.The game goal is to destroy geometric figures of the game world. A certain number of points is given for destroying each figure depending on the figure type and the current factor value. There are n types of geometric figures. The number of figures of type ki and figure cost ci is known for each figure type. A player gets ci·f  points for destroying one figure of type i, where f is the current factor. The factor value can be an integer number from 1 to t + 1, inclusive. At the beginning of the game the factor value is equal to 1. The factor is set to i + 1 after destruction of pi (1 ≤ i ≤ t) figures, so the (pi + 1)-th figure to be destroyed is considered with factor equal to i + 1.Your task is to determine the maximum number of points Vasya can get after he destroys all figures. Take into account that Vasya is so tough that he can destroy figures in any order chosen by him.",[]713"This is an interactive problem.Misha likes to play cooperative games with incomplete information. Today he suggested ten his friends to play a cooperative game ""Lake"".Misha has already come up with a field for the upcoming game. The field for this game is a directed graph consisting of two parts. The first part is a road along the coast of the lake which is a cycle of $$$c$$$ vertices. The second part is a path from home to the lake which is a chain of $$$t$$$ vertices, and there is an edge from the last vertex of this chain to the vertex of the road along the coast which has the most beautiful view of the lake, also known as the finish vertex. Misha decided to keep the field secret, so nobody knows neither $$$t$$$ nor $$$c$$$.  Note that each vertex of the field has exactly one outgoing edge and all the vertices except the home vertex and the finish vertex have exactly one ingoing edge. The home vertex has no incoming edges, the finish vertex has two incoming edges.At the beginning of the game pieces of all the ten players, indexed with consecutive integers from $$$0$$$ to $$$9$$$, are at the home vertex. After that on each turn some of the players can ask Misha to simultaneously move their pieces along the corresponding edges. Misha will not answer more than $$$q$$$ such queries. After each move Misha will tell players whose pieces are at the same vertices and whose pieces are at different vertices.The goal of the game is to move all the pieces to the finish vertex. Misha's friends have no idea how to win in such a game without knowledge of $$$c$$$, $$$t$$$ and $$$q$$$, but luckily they are your friends. Help them: coordinate their actions to win the game. Misha has drawn such a field that $$$1 \le t, c$$$, $$$(t+c) \leq 1000$$$ and $$$q = 3 \cdot (t+c)$$$.",['number theory']714"It is a simplified version of problem F2. The difference between them is the constraints (F1: $$$k \le 2$$$, F2: $$$k \le 10$$$).You are given an integer $$$n$$$. Find the minimum integer $$$x$$$ such that $$$x \ge n$$$ and the number $$$x$$$ is $$$k$$$-beautiful.A number is called $$$k$$$-beautiful if its decimal representation having no leading zeroes contains no more than $$$k$$$ different digits. E.g. if $$$k = 2$$$, the numbers $$$3434443$$$, $$$55550$$$, $$$777$$$ and $$$21$$$ are $$$k$$$-beautiful whereas the numbers $$$120$$$, $$$445435$$$ and $$$998244353$$$ are not.",[]715"Nick's company employed n people. Now Nick needs to build a tree hierarchy of «supervisor-surbodinate» relations in the company (this is to say that each employee, except one, has exactly one supervisor). There are m applications written in the following form: «employee ai is ready to become a supervisor of employee bi at extra cost ci». The qualification qj of each employee is known, and for each application the following is true: qai > qbi. Would you help Nick calculate the minimum cost of such a hierarchy, or find out that it is impossible to build it.",[]716"Berland has n cities connected by m bidirectional roads. No road connects a city to itself, and each pair of cities is connected by no more than one road. It is not guaranteed that you can get from any city to any other one, using only the existing roads.The President of Berland decided to make changes to the road system and instructed the Ministry of Transport to make this reform. Now, each road should be unidirectional (only lead from one city to another).In order not to cause great resentment among residents, the reform needs to be conducted so that there can be as few separate cities as possible. A city is considered separate, if no road leads into it, while it is allowed to have roads leading from this city.Help the Ministry of Transport to find the minimum possible number of separate cities after the reform.",['graphs']717"There is a game called ""I Wanna Be the Guy"", consisting of n levels. Little X and his friend Little Y are addicted to the game. Each of them wants to pass the whole game.Little X can pass only p levels of the game. And Little Y can pass only q levels of the game. You are given the indices of levels Little X can pass and the indices of levels Little Y can pass. Will Little X and Little Y pass the whole game, if they cooperate each other?",[]718"You finally woke up after this crazy dream and decided to walk around to clear your head. Outside you saw your house's fence — so plain and boring, that you'd like to repaint it.  You have a fence consisting of $$$n$$$ planks, where the $$$i$$$-th plank has the color $$$a_i$$$. You want to repaint the fence in such a way that the $$$i$$$-th plank has the color $$$b_i$$$.You've invited $$$m$$$ painters for this purpose. The $$$j$$$-th painter will arrive at the moment $$$j$$$ and will recolor exactly one plank to color $$$c_j$$$. For each painter you can choose which plank to recolor, but you can't turn them down, i. e. each painter has to color exactly one plank.Can you get the coloring $$$b$$$ you want? If it's possible, print for each painter which plank he must paint.",[]719"You are fed up with your messy room, so you decided to clean it up.Your room is a bracket sequence $$$s=s_{1}s_{2}\dots s_{n}$$$ of length $$$n$$$. Each character of this string is either an opening bracket '(' or a closing bracket ')'.In one operation you can choose any consecutive substring of $$$s$$$ and reverse it. In other words, you can choose any substring $$$s[l \dots r]=s_l, s_{l+1}, \dots, s_r$$$ and change the order of elements in it into $$$s_r, s_{r-1}, \dots, s_{l}$$$.For example, if you will decide to reverse substring $$$s[2 \dots 4]$$$ of string $$$s=$$$""((()))"" it will be equal to $$$s=$$$""()(())"".A regular (aka balanced) bracket sequence is a bracket sequence that can be transformed into a correct arithmetic expression by inserting characters '1' and '+' between the original characters of the sequence. For example, bracket sequences ""()()"", ""(())"" are regular (the resulting expressions are: ""(1)+(1)"", ""((1+1)+1)""), and "")("" and ""("" are not.A prefix of a string $$$s$$$ is a substring that starts at position $$$1$$$. For example, for $$$s=$$$""(())()"" there are $$$6$$$ prefixes: ""("", ""(("", ""(()"", ""(())"", ""(())("" and ""(())()"".In your opinion, a neat and clean room $$$s$$$ is a bracket sequence that:  the whole string $$$s$$$ is a regular bracket sequence;  and there are exactly $$$k$$$ prefixes of this sequence which are regular (including whole $$$s$$$ itself). For example, if $$$k = 2$$$, then ""(())()"" is a neat and clean room.You want to use at most $$$n$$$ operations to make your room neat and clean. Operations are applied one after another sequentially.It is guaranteed that the answer exists. Note that you do not need to minimize the number of operations: find any way to achieve the desired configuration in $$$n$$$ or less operations.",[]720"In Berland, $$$n$$$ different types of banknotes are used. Banknotes of the $$$i$$$-th type have denomination $$$10^{a_i}$$$ burles (burles are the currency used in Berland); the denomination of banknotes of the first type is exactly $$$1$$$.Let's denote $$$f(s)$$$ as the minimum number of banknotes required to represent exactly $$$s$$$ burles. For example, if the denominations of banknotes used in Berland are $$$1$$$, $$$10$$$ and $$$100$$$, then $$$f(59) = 14$$$: $$$9$$$ banknotes with denomination of $$$1$$$ burle and $$$5$$$ banknotes with denomination of $$$10$$$ burles can be used to represent exactly $$$9 \cdot 1 + 5 \cdot 10 = 59$$$ burles, and there's no way to do it with fewer banknotes.For a given integer $$$k$$$, find the minimum positive number of burles $$$s$$$ that cannot be represented with $$$k$$$ or fewer banknotes (that is, $$$f(s) > k$$$).",['number theory']721"Немногие знают, что сотрудники ВКонтакте могут менять цвет подсветки в куполе знаменитого Дома Зингера, где расположена штаб-квартира ВКонтакте. Для этого нужно всего лишь отправить сообщение с цветом в специальный чат «Зингер | color», а бот его распознает и сменит подсветку. При этом на время городских мероприятий смена цвета блокируется.Формально, бот обрабатывает три типа сообщений:   lock: заблокировать изменение цвета. Если оно и так заблокировано на данный момент, сообщение игнорируется.  unlock: разблокировать изменение цвета. Если оно и так разблокировано на данный момент, сообщение игнорируется.  red / orange / yellow / green / blue / indigo / violet: изменить цвет купола на заданный, если изменение цвета на данный момент не заблокировано. Вам дана история сообщений, полученных ботом, в хронологическом порядке. Считайте, что перед получением первого сообщения купол подсвечивается голубым (blue), а изменение цвета не заблокировано.В качестве эксперимента было решено поддержать в боте эффективную обработку редактирования сообщений. Вам дана последовательность пар вида $$$(i, msg)$$$, означающих, что $$$i$$$-е в хронологическом порядке сообщение было отредактировано и теперь имеет вид $$$msg$$$. Обратите внимание, что редактироваться может любое сообщение, и при редактировании сообщения бот должен обработать всю историю сообщений заново (в частности, перед обработкой первого сообщения цвет купола голубой, а изменение цвета не заблокировано).Определите, какой цвет будет у купола Дома Зингера до первой операции редактирования, а также после каждой операции редактирования.",[]722"After the mysterious disappearance of Ashish, his two favourite disciples Ishika and Hriday, were each left with one half of a secret message. These messages can each be represented by a permutation of size $$$n$$$. Let's call them $$$a$$$ and $$$b$$$.Note that a permutation of $$$n$$$ elements is a sequence of numbers $$$a_1, a_2, \ldots, a_n$$$, in which every number from $$$1$$$ to $$$n$$$ appears exactly once. The message can be decoded by an arrangement of sequence $$$a$$$ and $$$b$$$, such that the number of matching pairs of elements between them is maximum. A pair of elements $$$a_i$$$ and $$$b_j$$$ is said to match if:   $$$i = j$$$, that is, they are at the same index.  $$$a_i = b_j$$$ His two disciples are allowed to perform the following operation any number of times:   choose a number $$$k$$$ and cyclically shift one of the permutations to the left or right $$$k$$$ times. A single cyclic shift to the left on any permutation $$$c$$$ is an operation that sets $$$c_1:=c_2, c_2:=c_3, \ldots, c_n:=c_1$$$ simultaneously. Likewise, a single cyclic shift to the right on any permutation $$$c$$$ is an operation that sets $$$c_1:=c_n, c_2:=c_1, \ldots, c_n:=c_{n-1}$$$ simultaneously.Help Ishika and Hriday find the maximum number of pairs of elements that match after performing the operation any (possibly zero) number of times.",[]723"You are given two strings $$$s$$$ and $$$t$$$ of equal length $$$n$$$. In one move, you can swap any two adjacent characters of the string $$$s$$$.You need to find the minimal number of operations you need to make string $$$s$$$ lexicographically smaller than string $$$t$$$.A string $$$a$$$ is lexicographically smaller than a string $$$b$$$ if and only if one of the following holds:   $$$a$$$ is a prefix of $$$b$$$, but $$$a \ne b$$$;  in the first position where $$$a$$$ and $$$b$$$ differ, the string $$$a$$$ has a letter that appears earlier in the alphabet than the corresponding letter in $$$b$$$. ",['strings']724"You came to the exhibition and one exhibit has drawn your attention. It consists of $$$n$$$ stacks of blocks, where the $$$i$$$-th stack consists of $$$a_i$$$ blocks resting on the surface.The height of the exhibit is equal to $$$m$$$. Consequently, the number of blocks in each stack is less than or equal to $$$m$$$.There is a camera on the ceiling that sees the top view of the blocks and a camera on the right wall that sees the side view of the blocks. Find the maximum number of blocks you can remove such that the views for both the cameras would not change.Note, that while originally all blocks are stacked on the floor, it is not required for them to stay connected to the floor after some blocks are removed. There is no gravity in the whole exhibition, so no block would fall down, even if the block underneath is removed. It is not allowed to move blocks by hand either.",[]725"Gena loves sequences of numbers. Recently, he has discovered a new type of sequences which he called an almost arithmetical progression. A sequence is an almost arithmetical progression, if its elements can be represented as:  a1 = p, where p is some integer;  ai = ai - 1 + ( - 1)i + 1·q (i > 1), where q is some integer. Right now Gena has a piece of paper with sequence b, consisting of n integers. Help Gena, find there the longest subsequence of integers that is an almost arithmetical progression.Sequence s1,  s2,  ...,  sk is a subsequence of sequence b1,  b2,  ...,  bn, if there is such increasing sequence of indexes i1, i2, ..., ik (1  ≤  i1  <  i2  < ...   <  ik  ≤  n), that bij  =  sj. In other words, sequence s can be obtained from b by crossing out some elements.",[]726"This is the first subtask of problem F. The only differences between this and the second subtask are the constraints on the value of $$$m$$$ and the time limit. You need to solve both subtasks in order to hack this one.There are $$$n+1$$$ distinct colours in the universe, numbered $$$0$$$ through $$$n$$$. There is a strip of paper $$$m$$$ centimetres long initially painted with colour $$$0$$$. Alice took a brush and painted the strip using the following process. For each $$$i$$$ from $$$1$$$ to $$$n$$$, in this order, she picks two integers $$$0 \leq a_i < b_i \leq m$$$, such that the segment $$$[a_i, b_i]$$$ is currently painted with a single colour, and repaints it with colour $$$i$$$. Alice chose the segments in such a way that each centimetre is now painted in some colour other than $$$0$$$. Formally, the segment $$$[i-1, i]$$$ is painted with colour $$$c_i$$$ ($$$c_i \neq 0$$$). Every colour other than $$$0$$$ is visible on the strip.Count the number of different pairs of sequences $$$\{a_i\}_{i=1}^n$$$, $$$\{b_i\}_{i=1}^n$$$ that result in this configuration. Since this number may be large, output it modulo $$$998244353$$$.",[]727"The flag of Berland is such rectangular field n × m that satisfies following conditions:  Flag consists of three colors which correspond to letters 'R', 'G' and 'B'.  Flag consists of three equal in width and height stripes, parralel to each other and to sides of the flag. Each stripe has exactly one color.  Each color should be used in exactly one stripe. You are given a field n × m, consisting of characters 'R', 'G' and 'B'. Output ""YES"" (without quotes) if this field corresponds to correct flag of Berland. Otherwise, print ""NO"" (without quotes).",[]728"Monocarp is playing a strategy game. In the game, he recruits a squad to fight monsters. Before each battle, Monocarp has $$$C$$$ coins to spend on his squad.Before each battle starts, his squad is empty. Monocarp chooses one type of units and recruits no more units of that type than he can recruit with $$$C$$$ coins.There are $$$n$$$ types of units. Every unit type has three parameters:   $$$c_i$$$ — the cost of recruiting one unit of the $$$i$$$-th type;  $$$d_i$$$ — the damage that one unit of the $$$i$$$-th type deals in a second;  $$$h_i$$$ — the amount of health of one unit of the $$$i$$$-th type. Monocarp has to face $$$m$$$ monsters. Every monster has two parameters:   $$$D_j$$$ — the damage that the $$$j$$$-th monster deals in a second;  $$$H_j$$$ — the amount of health the $$$j$$$-th monster has. Monocarp has to fight only the $$$j$$$-th monster during the $$$j$$$-th battle. He wants all his recruited units to stay alive. Both Monocarp's squad and the monster attack continuously (not once per second) and at the same time. Thus, Monocarp wins the battle if and only if his squad kills the monster strictly faster than the monster kills one of his units. The time is compared with no rounding.For each monster, Monocarp wants to know the minimum amount of coins he has to spend to kill that monster. If this amount is greater than $$$C$$$, then report that it's impossible to kill that monster.",['math']729"Note that girls in Arpa’s land are really attractive.Arpa loves overnight parties. In the middle of one of these parties Mehrdad suddenly appeared. He saw n pairs of friends sitting around a table. i-th pair consisted of a boy, sitting on the ai-th chair, and his girlfriend, sitting on the bi-th chair. The chairs were numbered 1 through 2n in clockwise direction. There was exactly one person sitting on each chair.  There were two types of food: Kooft and Zahre-mar. Now Mehrdad wonders, was there any way to serve food for the guests such that:   Each person had exactly one type of food,  No boy had the same type of food as his girlfriend,  Among any three guests sitting on consecutive chairs, there was two of them who had different type of food. Note that chairs 2n and 1 are considered consecutive. Find the answer for the Mehrdad question. If it was possible, find some arrangement of food types that satisfies the conditions.",['graphs']730"Katya studies in a fifth grade. Recently her class studied right triangles and the Pythagorean theorem. It appeared, that there are triples of positive integers such that you can construct a right triangle with segments of lengths corresponding to triple. Such triples are called Pythagorean triples.For example, triples (3, 4, 5), (5, 12, 13) and (6, 8, 10) are Pythagorean triples.Here Katya wondered if she can specify the length of some side of right triangle and find any Pythagorean triple corresponding to such length? Note that the side which length is specified can be a cathetus as well as hypotenuse.Katya had no problems with completing this task. Will you do the same?","['math', 'number theory']"731"You are a mayor of Berlyatov. There are $$$n$$$ districts and $$$m$$$ two-way roads between them. The $$$i$$$-th road connects districts $$$x_i$$$ and $$$y_i$$$. The cost of travelling along this road is $$$w_i$$$. There is some path between each pair of districts, so the city is connected.There are $$$k$$$ delivery routes in Berlyatov. The $$$i$$$-th route is going from the district $$$a_i$$$ to the district $$$b_i$$$. There is one courier on each route and the courier will always choose the cheapest (minimum by total cost) path from the district $$$a_i$$$ to the district $$$b_i$$$ to deliver products.The route can go from the district to itself, some couriers routes can coincide (and you have to count them independently).You can make at most one road to have cost zero (i.e. you choose at most one road and change its cost with $$$0$$$).Let $$$d(x, y)$$$ be the cheapest cost of travel between districts $$$x$$$ and $$$y$$$.Your task is to find the minimum total courier routes cost you can achieve, if you optimally select the some road and change its cost with $$$0$$$. In other words, you have to find the minimum possible value of $$$\sum\limits_{i = 1}^{k} d(a_i, b_i)$$$ after applying the operation described above optimally.",['graphs']732"There are $$$n$$$ trees in a park, numbered from $$$1$$$ to $$$n$$$. The initial height of the $$$i$$$-th tree is $$$h_i$$$.You want to water these trees, so they all grow to the same height.The watering process goes as follows. You start watering trees at day $$$1$$$. During the $$$j$$$-th day you can:   Choose a tree and water it. If the day is odd (e.g. $$$1, 3, 5, 7, \dots$$$), then the height of the tree increases by $$$1$$$. If the day is even (e.g. $$$2, 4, 6, 8, \dots$$$), then the height of the tree increases by $$$2$$$.  Or skip a day without watering any tree. Note that you can't water more than one tree in a day. Your task is to determine the minimum number of days required to water the trees so they grow to the same height.You have to answer $$$t$$$ independent test cases.",['math']733"There is a grid with $$$r$$$ rows and $$$c$$$ columns, where the square on the $$$i$$$-th row and $$$j$$$-th column has an integer $$$a_{i, j}$$$ written on it. Initially, all elements are set to $$$0$$$. We are allowed to do the following operation:  Choose indices $$$1 \le i \le r$$$ and $$$1 \le j \le c$$$, then replace all values on the same row or column as $$$(i, j)$$$ with the value xor $$$1$$$. In other words, for all $$$a_{x, y}$$$ where $$$x=i$$$ or $$$y=j$$$ or both, replace $$$a_{x, y}$$$ with $$$a_{x, y}$$$ xor $$$1$$$. You want to form grid $$$b$$$ by doing the above operations a finite number of times. However, some elements of $$$b$$$ are missing and are replaced with '?' instead.Let $$$k$$$ be the number of '?' characters. Among all the $$$2^k$$$ ways of filling up the grid $$$b$$$ by replacing each '?' with '0' or '1', count the number of grids, that can be formed by doing the above operation a finite number of times, starting from the grid filled with $$$0$$$. As this number can be large, output it modulo $$$998244353$$$.","['math', 'graphs']"734"You are the owner of a harvesting field which can be modeled as an infinite line, whose positions are identified by integers.It will rain for the next $$$n$$$ days. On the $$$i$$$-th day, the rain will be centered at position $$$x_i$$$ and it will have intensity $$$p_i$$$. Due to these rains, some rainfall will accumulate; let $$$a_j$$$ be the amount of rainfall accumulated at integer position $$$j$$$. Initially $$$a_j$$$ is $$$0$$$, and it will increase by $$$\max(0,p_i-|x_i-j|)$$$ after the $$$i$$$-th day's rain.A flood will hit your field if, at any moment, there is a position $$$j$$$ with accumulated rainfall $$$a_j>m$$$.You can use a magical spell to erase exactly one day's rain, i.e., setting $$$p_i=0$$$. For each $$$i$$$ from $$$1$$$ to $$$n$$$, check whether in case of erasing the $$$i$$$-th day's rain there is no flood.",[]735"You are organizing a boxing tournament, where $$$n$$$ boxers will participate ($$$n$$$ is a power of $$$2$$$), and your friend is one of them. All boxers have different strength from $$$1$$$ to $$$n$$$, and boxer $$$i$$$ wins in the match against boxer $$$j$$$ if and only if $$$i$$$ is stronger than $$$j$$$.The tournament will be organized as follows: $$$n$$$ boxers will be divided into pairs; the loser in each pair leaves the tournament, and $$$\frac{n}{2}$$$ winners advance to the next stage, where they are divided into pairs again, and the winners in all pairs advance to the next stage, and so on, until only one boxer remains (who is declared the winner).Your friend really wants to win the tournament, but he may be not the strongest boxer. To help your friend win the tournament, you may bribe his opponents: if your friend is fighting with a boxer you have bribed, your friend wins even if his strength is lower.Furthermore, during each stage you distribute the boxers into pairs as you wish.The boxer with strength $$$i$$$ can be bribed if you pay him $$$a_i$$$ dollars. What is the minimum number of dollars you have to spend to make your friend win the tournament, provided that you arrange the boxers into pairs during each stage as you wish?",[]736"One of Timofey's birthday presents is a colourbook in a shape of an infinite plane. On the plane n rectangles with sides parallel to coordinate axes are situated. All sides of the rectangles have odd length. Rectangles cannot intersect, but they can touch each other.Help Timofey to color his rectangles in 4 different colors in such a way that every two rectangles touching each other by side would have different color, or determine that it is impossible.Two rectangles intersect if their intersection has positive area. Two rectangles touch by sides if there is a pair of sides such that their intersection has non-zero length    The picture corresponds to the first example ",['geometry']737"One of Arkady's friends works at a huge radio telescope. A few decades ago the telescope has sent a signal $$$s$$$ towards a faraway galaxy. Recently they've received a response $$$t$$$ which they believe to be a response from aliens! The scientists now want to check if the signal $$$t$$$ is similar to $$$s$$$.The original signal $$$s$$$ was a sequence of zeros and ones (everyone knows that binary code is the universe-wide language). The returned signal $$$t$$$, however, does not look as easy as $$$s$$$, but the scientists don't give up! They represented $$$t$$$ as a sequence of English letters and say that $$$t$$$ is similar to $$$s$$$ if you can replace all zeros in $$$s$$$ with some string $$$r_0$$$ and all ones in $$$s$$$ with some other string $$$r_1$$$ and obtain $$$t$$$. The strings $$$r_0$$$ and $$$r_1$$$ must be different and non-empty.Please help Arkady's friend and find the number of possible replacements for zeros and ones (the number of pairs of strings $$$r_0$$$ and $$$r_1$$$) that transform $$$s$$$ to $$$t$$$.",['strings']738"Happy PMP is freshman and he is learning about algorithmic problems. He enjoys playing algorithmic games a lot.One of the seniors gave Happy PMP a nice game. He is given two permutations of numbers 1 through n and is asked to convert the first one to the second. In one move he can remove the last number from the permutation of numbers and inserts it back in an arbitrary position. He can either insert last number between any two consecutive numbers, or he can place it at the beginning of the permutation.Happy PMP has an algorithm that solves the problem. But it is not fast enough. He wants to know the minimum number of moves to convert the first permutation to the second. ",[]739"You are given circular array a0, a1, ..., an - 1. There are two types of operations with it:   inc(lf, rg, v) — this operation increases each element on the segment [lf, rg] (inclusively) by v;  rmq(lf, rg) — this operation returns minimal value on the segment [lf, rg] (inclusively). Assume segments to be circular, so if n = 5 and lf = 3, rg = 1, it means the index sequence: 3, 4, 0, 1.Write program to process given sequence of operations.",[]740"In this task you need to process a set of stock exchange orders and use them to create order book.An order is an instruction of some participant to buy or sell stocks on stock exchange. The order number i has price pi, direction di — buy or sell, and integer qi. This means that the participant is ready to buy or sell qi stocks at price pi for one stock. A value qi is also known as a volume of an order.All orders with the same price p and direction d are merged into one aggregated order with price p and direction d. The volume of such order is a sum of volumes of the initial orders.An order book is a list of aggregated orders, the first part of which contains sell orders sorted by price in descending order, the second contains buy orders also sorted by price in descending order.An order book of depth s contains s best aggregated orders for each direction. A buy order is better if it has higher price and a sell order is better if it has lower price. If there are less than s aggregated orders for some direction then all of them will be in the final order book.You are given n stock exhange orders. Your task is to print order book of depth s for these orders.",[]741"There are n points marked on the plane. The points are situated in such a way that they form a regular polygon (marked points are its vertices, and they are numbered in counter-clockwise order). You can draw n - 1 segments, each connecting any two marked points, in such a way that all points have to be connected with each other (directly or indirectly).But there are some restrictions. Firstly, some pairs of points cannot be connected directly and have to be connected undirectly. Secondly, the segments you draw must not intersect in any point apart from the marked points (that is, if any two segments intersect and their intersection is not a marked point, then the picture you have drawn is invalid).How many ways are there to connect all vertices with n - 1 segments? Two ways are considered different iff there exist some pair of points such that a segment is drawn between them in the first way of connection, but it is not drawn between these points in the second one. Since the answer might be large, output it modulo 109 + 7.",['graphs']742"An array $$$b$$$ of length $$$k$$$ is called good if its arithmetic mean is equal to $$$1$$$. More formally, if $$$$$$\frac{b_1 + \cdots + b_k}{k}=1.$$$$$$Note that the value $$$\frac{b_1+\cdots+b_k}{k}$$$ is not rounded up or down. For example, the array $$$[1,1,1,2]$$$ has an arithmetic mean of $$$1.25$$$, which is not equal to $$$1$$$.You are given an integer array $$$a$$$ of length $$$n$$$. In an operation, you can append a non-negative integer to the end of the array. What's the minimum number of operations required to make the array good?We have a proof that it is always possible with finitely many operations.",['math']743"Ivan is playing a strange game.He has a matrix a with n rows and m columns. Each element of the matrix is equal to either 0 or 1. Rows and columns are 1-indexed. Ivan can replace any number of ones in this matrix with zeroes. After that, his score in the game will be calculated as follows:  Initially Ivan's score is 0;  In each column, Ivan will find the topmost 1 (that is, if the current column is j, then he will find minimum i such that ai, j = 1). If there are no 1's in the column, this column is skipped;  Ivan will look at the next min(k, n - i + 1) elements in this column (starting from the element he found) and count the number of 1's among these elements. This number will be added to his score. Of course, Ivan wants to maximize his score in this strange game. Also he doesn't want to change many elements, so he will replace the minimum possible number of ones with zeroes. Help him to determine the maximum possible score he can get and the minimum possible number of replacements required to achieve that score.",[]744"Vlad, like everyone else, loves to sleep very much.Every day Vlad has to do $$$n$$$ things, each at a certain time. For each of these things, he has an alarm clock set, the $$$i$$$-th of them is triggered on $$$h_i$$$ hours $$$m_i$$$ minutes every day ($$$0 \le h_i < 24, 0 \le m_i < 60$$$). Vlad uses the $$$24$$$-hour time format, so after $$$h=12, m=59$$$ comes $$$h=13, m=0$$$ and after $$$h=23, m=59$$$ comes $$$h=0, m=0$$$.This time Vlad went to bed at $$$H$$$ hours $$$M$$$ minutes ($$$0 \le H < 24, 0 \le M < 60$$$) and asks you to answer: how much he will be able to sleep until the next alarm clock.If any alarm clock rings at the time when he went to bed, then he will sleep for a period of time of length $$$0$$$.",['math']745"At the foot of Liyushan Mountain, $$$n$$$ tents will be carefully arranged to provide accommodation for those who are willing to experience the joy of approaching nature, the tranquility of the night, and the bright starry sky.The $$$i$$$-th tent is located at the point of $$$(x_i, y_i)$$$ and has a weight of $$$w_i$$$. A tent is important if and only if both $$$x_i$$$ and $$$y_i$$$ are even. You need to remove some tents such that for each remaining important tent $$$(x, y)$$$, there do not exist $$$3$$$ other tents $$$(x'_1, y'_1)$$$, $$$(x'_2, y'_2)$$$ and $$$(x'_3, y'_3)$$$ such that both conditions are true:   $$$|x'_j-x|, |y'_j - y|\leq 1$$$ for all $$$j \in \{1, 2, 3\}$$$, and  these four tents form a parallelogram (or a rectangle) and one of its sides is parallel to the $$$x$$$-axis. Please maximize the sum of the weights of the tents that are not removed. Print the maximum value.",['graphs']746"You are given a non-decreasing array of non-negative integers $$$a_1, a_2, \ldots, a_n$$$. Also you are given a positive integer $$$k$$$.You want to find $$$m$$$ non-decreasing arrays of non-negative integers $$$b_1, b_2, \ldots, b_m$$$, such that:  The size of $$$b_i$$$ is equal to $$$n$$$ for all $$$1 \leq i \leq m$$$.  For all $$$1 \leq j \leq n$$$, $$$a_j = b_{1, j} + b_{2, j} + \ldots + b_{m, j}$$$. In the other word, array $$$a$$$ is the sum of arrays $$$b_i$$$.  The number of different elements in the array $$$b_i$$$ is at most $$$k$$$ for all $$$1 \leq i \leq m$$$. Find the minimum possible value of $$$m$$$, or report that there is no possible $$$m$$$.",['math']747"Treeland consists of $$$n$$$ cities and $$$n-1$$$ roads. Each road is bidirectional and connects two distinct cities. From any city you can get to any other city by roads. Yes, you are right — the country's topology is an undirected tree.There are some private road companies in Treeland. The government decided to sell roads to the companies. Each road will belong to one company and a company can own multiple roads.The government is afraid to look unfair. They think that people in a city can consider them unfair if there is one company which owns two or more roads entering the city. The government wants to make such privatization that the number of such cities doesn't exceed $$$k$$$ and the number of companies taking part in the privatization is minimal.Choose the number of companies $$$r$$$ such that it is possible to assign each road to one company in such a way that the number of cities that have two or more roads of one company is at most $$$k$$$. In other words, if for a city all the roads belong to the different companies then the city is good. Your task is to find the minimal $$$r$$$ that there is such assignment to companies from $$$1$$$ to $$$r$$$ that the number of cities which are not good doesn't exceed $$$k$$$.    The picture illustrates the first example ($$$n=6, k=2$$$). The answer contains $$$r=2$$$ companies. Numbers on the edges denote edge indices. Edge colors mean companies: red corresponds to the first company, blue corresponds to the second company. The gray vertex (number $$$3$$$) is not good. The number of such vertices (just one) doesn't exceed $$$k=2$$$. It is impossible to have at most $$$k=2$$$ not good cities in case of one company. ","['graphs', 'trees']"748"Dima got into number sequences. Now he's got sequence a1, a2, ..., an, consisting of n positive integers. Also, Dima has got a function f(x), which can be defined with the following recurrence:  f(0) = 0;  f(2·x) = f(x);  f(2·x + 1) = f(x) + 1. Dima wonders, how many pairs of indexes (i, j) (1 ≤ i < j ≤ n) are there, such that f(ai) = f(aj). Help him, count the number of such pairs. ",['math']749"Anton likes to play chess. Also, he likes to do programming. That is why he decided to write the program that plays chess. However, he finds the game on 8 to 8 board to too simple, he uses an infinite one instead.The first task he faced is to check whether the king is in check. Anton doesn't know how to implement this so he asks you to help.Consider that an infinite chess board contains one white king and the number of black pieces. There are only rooks, bishops and queens, as the other pieces are not supported yet. The white king is said to be in check if at least one black piece can reach the cell with the king in one move. Help Anton and write the program that for the given position determines whether the white king is in check.Remainder, on how do chess pieces move:   Bishop moves any number of cells diagonally, but it can't ""leap"" over the occupied cells.  Rook moves any number of cells horizontally or vertically, but it also can't ""leap"" over the occupied cells.  Queen is able to move any number of cells horizontally, vertically or diagonally, but it also can't ""leap"". ",[]750"Being a programmer, you like arrays a lot. For your birthday, your friends have given you an array a consisting of n distinct integers.Unfortunately, the size of a is too small. You want a bigger array! Your friends agree to give you a bigger array, but only if you are able to answer the following question correctly: is it possible to sort the array a (in increasing order) by reversing exactly one segment of a? See definitions of segment and reversing in the notes.",[]751"Since you are the best Wraith King, Nizhniy Magazin «Mir» at the centre of Vinnytsia is offering you a discount.You are given an array a of length n and an integer c. The value of some array b of length k is the sum of its elements except for the  smallest. For example, the value of the array [3, 1, 6, 5, 2] with c = 2 is 3 + 6 + 5 = 14.Among all possible partitions of a into contiguous subarrays output the smallest possible sum of the values of these subarrays.",['math']752"There was an electronic store heist last night.All keyboards which were in the store yesterday were numbered in ascending order from some integer number $$$x$$$. For example, if $$$x = 4$$$ and there were $$$3$$$ keyboards in the store, then the devices had indices $$$4$$$, $$$5$$$ and $$$6$$$, and if $$$x = 10$$$ and there were $$$7$$$ of them then the keyboards had indices $$$10$$$, $$$11$$$, $$$12$$$, $$$13$$$, $$$14$$$, $$$15$$$ and $$$16$$$.After the heist, only $$$n$$$ keyboards remain, and they have indices $$$a_1, a_2, \dots, a_n$$$. Calculate the minimum possible number of keyboards that have been stolen. The staff remember neither $$$x$$$ nor the number of keyboards in the store before the heist.",[]753"There are $$$n$$$ TV shows you want to watch. Suppose the whole time is split into equal parts called ""minutes"". The $$$i$$$-th of the shows is going from $$$l_i$$$-th to $$$r_i$$$-th minute, both ends inclusive.You need a TV to watch a TV show and you can't watch two TV shows which air at the same time on the same TV, so it is possible you will need multiple TVs in some minutes. For example, if segments $$$[l_i, r_i]$$$ and $$$[l_j, r_j]$$$ intersect, then shows $$$i$$$ and $$$j$$$ can't be watched simultaneously on one TV.Once you start watching a show on some TV it is not possible to ""move"" it to another TV (since it would be too distracting), or to watch another show on the same TV until this show ends.There is a TV Rental shop near you. It rents a TV for $$$x$$$ rupees, and charges $$$y$$$ ($$$y < x$$$) rupees for every extra minute you keep the TV. So in order to rent a TV for minutes $$$[a; b]$$$ you will need to pay $$$x + y \cdot (b - a)$$$. You can assume, that taking and returning of the TV doesn't take any time and doesn't distract from watching other TV shows. Find the minimum possible cost to view all shows. Since this value could be too large, print it modulo $$$10^9 + 7$$$.",[]754"You are given a huge decimal number consisting of $$$n$$$ digits. It is guaranteed that this number has no leading zeros. Each digit of this number is either 0 or 1.You may perform several (possibly zero) operations with this number. During each operation you are allowed to change any digit of your number; you may change 0 to 1 or 1 to 0. It is possible that after some operation you can obtain a number with leading zeroes, but it does not matter for this problem.You are also given two integers $$$0 \le y < x < n$$$. Your task is to calculate the minimum number of operations you should perform to obtain the number that has remainder $$$10^y$$$ modulo $$$10^x$$$. In other words, the obtained number should have remainder $$$10^y$$$ when divided by $$$10^x$$$.",['math']755"An array of integers $$$p_1, p_2, \dots, p_n$$$ is called a permutation if it contains each number from $$$1$$$ to $$$n$$$ exactly once. For example, the following arrays are permutations: $$$[3, 1, 2]$$$, $$$[1]$$$, $$$[1, 2, 3, 4, 5]$$$ and $$$[4, 3, 1, 2]$$$. The following arrays are not permutations: $$$[2]$$$, $$$[1, 1]$$$, $$$[2, 3, 4]$$$.Polycarp invented a really cool permutation $$$p_1, p_2, \dots, p_n$$$ of length $$$n$$$. It is very disappointing, but he forgot this permutation. He only remembers the array $$$q_1, q_2, \dots, q_{n-1}$$$ of length $$$n-1$$$, where $$$q_i=p_{i+1}-p_i$$$.Given $$$n$$$ and $$$q=q_1, q_2, \dots, q_{n-1}$$$, help Polycarp restore the invented permutation.",['math']756"This is the hard version of the problem. The only difference between the two versions is that the harder version asks additionally for a minimum number of subsegments.Tokitsukaze has a binary string $$$s$$$ of length $$$n$$$, consisting only of zeros and ones, $$$n$$$ is even.Now Tokitsukaze divides $$$s$$$ into the minimum number of contiguous subsegments, and for each subsegment, all bits in each subsegment are the same. After that, $$$s$$$ is considered good if the lengths of all subsegments are even.For example, if $$$s$$$ is ""11001111"", it will be divided into ""11"", ""00"" and ""1111"". Their lengths are $$$2$$$, $$$2$$$, $$$4$$$ respectively, which are all even numbers, so ""11001111"" is good. Another example, if $$$s$$$ is ""1110011000"", it will be divided into ""111"", ""00"", ""11"" and ""000"", and their lengths are $$$3$$$, $$$2$$$, $$$2$$$, $$$3$$$. Obviously, ""1110011000"" is not good.Tokitsukaze wants to make $$$s$$$ good by changing the values of some positions in $$$s$$$. Specifically, she can perform the operation any number of times: change the value of $$$s_i$$$ to '0' or '1' ($$$1 \leq i \leq n$$$). Can you tell her the minimum number of operations to make $$$s$$$ good? Meanwhile, she also wants to know the minimum number of subsegments that $$$s$$$ can be divided into among all solutions with the minimum number of operations.",[]757"Pupils decided to go to amusement park. Some of them were with parents. In total, n people came to the park and they all want to get to the most extreme attraction and roll on it exactly once.Tickets for group of x people are sold on the attraction, there should be at least one adult in each group (it is possible that the group consists of one adult). The ticket price for such group is c1 + c2·(x - 1)2 (in particular, if the group consists of one person, then the price is c1). All pupils who came to the park and their parents decided to split into groups in such a way that each visitor join exactly one group, and the total price of visiting the most extreme attraction is as low as possible. You are to determine this minimum possible total price. There should be at least one adult in each group. ",[]758"The life goes up and down, just like nice sequences. Sequence t1, t2, ..., tn is called nice if the following two conditions are satisfied:   ti < ti + 1 for each odd i < n;  ti > ti + 1 for each even i < n. For example, sequences (2, 8), (1, 5, 1) and (2, 5, 1, 100, 99, 120) are nice, while (1, 1), (1, 2, 3) and (2, 5, 3, 2) are not.Bear Limak has a sequence of positive integers t1, t2, ..., tn. This sequence is not nice now and Limak wants to fix it by a single swap. He is going to choose two indices i < j and swap elements ti and tj in order to get a nice sequence. Count the number of ways to do so. Two ways are considered different if indices of elements chosen for a swap are different.",[]759"The R1 company wants to hold a web search championship. There were n computers given for the competition, each of them is connected to the Internet. The organizers believe that the data transfer speed directly affects the result. The higher the speed of the Internet is, the faster the participant will find the necessary information. Therefore, before the competition started, each computer had its maximum possible data transfer speed measured. On the i-th computer it was ai kilobits per second.There will be k participants competing in the championship, each should get a separate computer. The organizing company does not want any of the participants to have an advantage over the others, so they want to provide the same data transfer speed to each participant's computer. Also, the organizers want to create the most comfortable conditions for the participants, so the data transfer speed on the participants' computers should be as large as possible.The network settings of the R1 company has a special option that lets you to cut the initial maximum data transfer speed of any computer to any lower speed. How should the R1 company configure the network using the described option so that at least k of n computers had the same data transfer speed and the data transfer speed on these computers was as large as possible?",[]760"You are given an integer a that consists of n digits. You are also given a sequence of digits s of length m. The digit in position j (1 ≤ j ≤ m) of sequence s means that you can choose an arbitrary position i (1 ≤ i ≤ n) in a and replace the digit in the chosen position i with sj. Each element in the sequence s can participate in no more than one replacing operation.Your task is to perform such sequence of replacements, that the given number a gets maximum value. You are allowed to use not all elements from s.",[]761"Dima has a birthday soon! It's a big day! Saryozha's present to Dima is that Seryozha won't be in the room and won't disturb Dima and Inna as they celebrate the birthday. Inna's present to Dima is a stack, a queue and a deck.Inna wants her present to show Dima how great a programmer he is. For that, she is going to give Dima commands one by one. There are two types of commands:  Add a given number into one of containers. For the queue and the stack, you can add elements only to the end. For the deck, you can add elements to the beginning and to the end.  Extract a number from each of at most three distinct containers. Tell all extracted numbers to Inna and then empty all containers. In the queue container you can extract numbers only from the beginning. In the stack container you can extract numbers only from the end. In the deck number you can extract numbers from the beginning and from the end. You cannot extract numbers from empty containers. Every time Dima makes a command of the second type, Inna kisses Dima some (possibly zero) number of times. Dima knows Inna perfectly well, he is sure that this number equals the sum of numbers he extracts from containers during this operation.As we've said before, Dima knows Inna perfectly well and he knows which commands Inna will give to Dima and the order of the commands. Help Dima find the strategy that lets him give as more kisses as possible for his birthday!",[]762"Alice is visiting New York City. To make the trip fun, Alice will take photos of the city skyline and give the set of photos as a present to Bob. However, she wants to find the set of photos with maximum beauty and she needs your help. There are $$$n$$$ buildings in the city, the $$$i$$$-th of them has positive height $$$h_i$$$. All $$$n$$$ building heights in the city are different. In addition, each building has a beauty value $$$b_i$$$. Note that beauty can be positive or negative, as there are ugly buildings in the city too. A set of photos consists of one or more photos of the buildings in the skyline. Each photo includes one or more buildings in the skyline that form a contiguous segment of indices. Each building needs to be in exactly one photo. This means that if a building does not appear in any photo, or if a building appears in more than one photo, the set of pictures is not valid. The beauty of a photo is equivalent to the beauty $$$b_i$$$ of the shortest building in it. The total beauty of a set of photos is the sum of the beauty of all photos in it. Help Alice to find the maximum beauty a valid set of photos can have. ",[]763"Many computer strategy games require building cities, recruiting army, conquering tribes, collecting resources. Sometimes it leads to interesting problems. Let's suppose that your task is to build a square city. The world map uses the Cartesian coordinates. The sides of the city should be parallel to coordinate axes. The map contains mines with valuable resources, located at some points with integer coordinates. The sizes of mines are relatively small, i.e. they can be treated as points. The city should be built in such a way that all the mines are inside or on the border of the city square. Building a city takes large amount of money depending on the size of the city, so you have to build the city with the minimum area. Given the positions of the mines find the minimum possible area of the city.",[]764"You are given an array $$$a$$$ of $$$2n$$$ distinct integers. You want to arrange the elements of the array in a circle such that no element is equal to the the arithmetic mean of its $$$2$$$ neighbours.More formally, find an array $$$b$$$, such that: $$$b$$$ is a permutation of $$$a$$$.For every $$$i$$$ from $$$1$$$ to $$$2n$$$, $$$b_i \neq \frac{b_{i-1}+b_{i+1}}{2}$$$, where $$$b_0 = b_{2n}$$$ and $$$b_{2n+1} = b_1$$$. It can be proved that under the constraints of this problem, such array $$$b$$$ always exists.",[]765"Petya and Vasya arranged a game. The game runs by the following rules. Players have a directed graph consisting of n vertices and m edges. One of the vertices contains a chip. Initially the chip is located at vertex s. Players take turns moving the chip along some edge of the graph. Petya goes first. Player who can't move the chip loses. If the game lasts for 106 turns the draw is announced.Vasya was performing big laboratory work in ""Spelling and parts of speech"" at night before the game, so he fell asleep at the very beginning of the game. Petya decided to take the advantage of this situation and make both Petya's and Vasya's moves.Your task is to help Petya find out if he can win the game or at least draw a tie.","['graphs', 'games']"766"Oh no, on the first exam Madoka got this hard problem:Given integer $$$n$$$ and $$$m$$$ pairs of integers ($$$v_i, u_i$$$). Also there is an array $$$b_1, b_2, \ldots, b_n$$$, initially filled with zeros.Then for each index $$$i$$$, where $$$1 \leq i \leq m$$$, perform either $$$b_{v_i} := b_{v_i} - 1$$$ and $$$b_{u_i} := b_{u_i} + 1$$$, or $$$b_{v_i} := b_{v_i} + 1$$$ and $$$b_{u_i} := b_{u_i} - 1$$$. Note that exactly one of these operations should be performed for every $$$i$$$.Also there is an array $$$s$$$ of length $$$n$$$ consisting of $$$0$$$ and $$$1$$$. And there is an array $$$a_1, a_2, \ldots, a_n$$$, where it is guaranteed, that if $$$s_i = 0$$$ holds, then $$$a_i = 0$$$.Help Madoka and determine whenever it is possible to perform operations in such way that for every $$$i$$$, where $$$s_i = 1$$$ it holds that $$$a_i = b_i$$$. If it possible you should also provide Madoka with a way to perform operations.",['graphs']767You have a blackboard and initially only an odd number $$$x$$$ is written on it. Your goal is to write the number $$$1$$$ on the blackboard.You may write new numbers on the blackboard with the following two operations.   You may take two numbers (not necessarily distinct) already on the blackboard and write their sum on the blackboard. The two numbers you have chosen remain on the blackboard.  You may take two numbers (not necessarily distinct) already on the blackboard and write their bitwise XOR on the blackboard. The two numbers you have chosen remain on the blackboard.  Perform a sequence of operations such that at the end the number $$$1$$$ is on the blackboard.,"['math', 'number theory']"768"Ancient Egyptians are known to have used a large set of symbols  to write on the walls of the temples. Fafa and Fifa went to one of the temples and found two non-empty words S1 and S2 of equal lengths on the wall of temple written one below the other. Since this temple is very ancient, some symbols from the words were erased. The symbols in the set  have equal probability for being in the position of any erased symbol.Fifa challenged Fafa to calculate the probability that S1 is lexicographically greater than S2. Can you help Fafa with this task?You know that , i. e. there were m distinct characters in Egyptians' alphabet, in this problem these characters are denoted by integers from 1 to m in alphabet order. A word x is lexicographically greater than a word y of the same length, if the words are same up to some position, and then the word x has a larger character, than the word y.We can prove that the probability equals to some fraction , where P and Q are coprime integers, and . Print as the answer the value , i. e. such a non-negative integer less than 109 + 7, such that , where  means that a and b give the same remainders when divided by m.","['math', 'probabilities']"769"Bit Lightyear, to the ANDfinity and beyond!After graduating from computer sciences, Vlad has been awarded an array $$$a_1,a_2,\ldots,a_n$$$ of $$$n$$$ non-negative integers. As it is natural, he wanted to construct a graph consisting of $$$n$$$ vertices, numbered $$$1, 2,\ldots, n$$$. He decided to add an edge between $$$i$$$ and $$$j$$$ if and only if $$$a_i \& a_j > 0$$$, where $$$\&$$$ denotes the bitwise AND operation.Vlad also wants the graph to be connected, which might not be the case initially. In order to satisfy that, he can do the following two types of operations on the array:  Choose some element $$$a_i$$$ and increment it by $$$1$$$.  Choose some element $$$a_i$$$ and decrement it by $$$1$$$ (possible only if $$$a_i > 0$$$). It can be proven that there exists a finite sequence of operations such that the graph will be connected. So, can you please help Vlad find the minimum possible number of operations to do that and also provide the way how to do that?",['graphs']770"Sasha lives in a big happy family. At the Man's Day all the men of the family gather to celebrate it following their own traditions. There are n men in Sasha's family, so let's number them with integers from 1 to n.Each man has at most one father but may have arbitrary number of sons.Man number A is considered to be the ancestor of the man number B if at least one of the following conditions is satisfied:   A = B;  the man number A is the father of the man number B;  there is a man number C, such that the man number A is his ancestor and the man number C is the father of the man number B. Of course, if the man number A is an ancestor of the man number B and A ≠ B, then the man number B is not an ancestor of the man number A.The tradition of the Sasha's family is to give gifts at the Man's Day. Because giving gifts in a normal way is boring, each year the following happens.  A list of candidates is prepared, containing some (possibly all) of the n men in some order.  Each of the n men decides to give a gift.  In order to choose a person to give a gift to, man A looks through the list and picks the first man B in the list, such that B is an ancestor of A and gives him a gift. Note that according to definition it may happen that a person gives a gift to himself.  If there is no ancestor of a person in the list, he becomes sad and leaves the celebration without giving a gift to anyone. This year you have decided to help in organizing celebration and asked each of the n men, who do they want to give presents to (this person is chosen only among ancestors). Are you able to make a list of candidates, such that all the wishes will be satisfied if they give gifts according to the process described above?","['graphs', 'trees']"771"Vasiliy lives at point (a, b) of the coordinate plane. He is hurrying up to work so he wants to get out of his house as soon as possible. New app suggested n available Beru-taxi nearby. The i-th taxi is located at point (xi, yi) and moves with a speed vi. Consider that each of n drivers will move directly to Vasiliy and with a maximum possible speed. Compute the minimum time when Vasiliy will get in any of Beru-taxi cars.",['geometry']772"Volodya likes listening to heavy metal and (occasionally) reading. No wonder Volodya is especially interested in texts concerning his favourite music style.Volodya calls a string powerful if it starts with ""heavy"" and ends with ""metal"". Finding all powerful substrings (by substring Volodya means a subsequence of consecutive characters in a string) in a given text makes our hero especially joyful. Recently he felt an enormous fit of energy while reading a certain text. So Volodya decided to count all powerful substrings in this text and brag about it all day long. Help him in this difficult task. Two substrings are considered different if they appear at the different positions in the text.For simplicity, let us assume that Volodya's text can be represented as a single string.",['strings']773This is the easy version of the problem. The difference between the versions is in the number of possible operations that can be made. You can make hacks if and only if you solved both versions of the problem.You are given a binary table of size $$$n \times m$$$. This table consists of symbols $$$0$$$ and $$$1$$$.You can make such operation: select $$$3$$$ different cells that belong to one $$$2 \times 2$$$ square and change the symbols in these cells (change $$$0$$$ to $$$1$$$ and $$$1$$$ to $$$0$$$).Your task is to make all symbols in the table equal to $$$0$$$. You are allowed to make at most $$$3nm$$$ operations. You don't need to minimize the number of operations.It can be proved that it is always possible.,[]774"This is the hard version of the problem. The only difference is that in this version $$$0 \leq k \leq 20$$$.There is an array $$$a_1, a_2, \ldots, a_n$$$ of $$$n$$$ positive integers. You should divide it into a minimal number of continuous segments, such that in each segment there are no two numbers (on different positions), whose product is a perfect square.Moreover, it is allowed to do at most $$$k$$$ such operations before the division: choose a number in the array and change its value to any positive integer.What is the minimum number of continuous segments you should use if you will make changes optimally?","['math', 'number theory']"775"A matrix of size $$$n \times m$$$ is called nice, if all rows and columns of the matrix are palindromes. A sequence of integers $$$(a_1, a_2, \dots , a_k)$$$ is a palindrome, if for any integer $$$i$$$ ($$$1 \le i \le k$$$) the equality $$$a_i = a_{k - i + 1}$$$ holds.Sasha owns a matrix $$$a$$$ of size $$$n \times m$$$. In one operation he can increase or decrease any number in the matrix by one. Sasha wants to make the matrix nice. He is interested what is the minimum number of operations he needs.Help him!",['math']776"There are n students studying in the 6th grade, in group ""B"" of a berland secondary school. Every one of them has exactly one friend whom he calls when he has some news. Let us denote the friend of the person number i by g(i). Note that the friendships are not mutual, i.e. g(g(i)) is not necessarily equal to i.On day i the person numbered as ai learns the news with the rating of bi (bi ≥ 1). He phones the friend immediately and tells it. While he is doing it, the news becomes old and its rating falls a little and becomes equal to bi - 1. The friend does the same thing — he also calls his friend and also tells the news. The friend of the friend gets the news already rated as bi - 2. It all continues until the rating of the news reaches zero as nobody wants to tell the news with zero rating. More formally, everybody acts like this: if a person x learns the news with a non-zero rating y, he calls his friend g(i) and his friend learns the news with the rating of y - 1 and, if it is possible, continues the process.Let us note that during a day one and the same person may call his friend and tell him one and the same news with different ratings. Thus, the news with the rating of bi will lead to as much as bi calls.Your task is to count the values of resi — how many students learned their first news on day i.The values of bi are known initially, whereas ai is determined from the following formula:  where mod stands for the operation of taking the excess from the cleavage, res0 is considered equal to zero and vi — some given integers.",[]777"Let's call a non-empty sequence of positive integers a1, a2... ak coprime if the greatest common divisor of all elements of this sequence is equal to 1.Given an array a consisting of n positive integers, find the number of its coprime subsequences. Since the answer may be very large, print it modulo 109 + 7.Note that two subsequences are considered different if chosen indices are different. For example, in the array [1, 1] there are 3 different subsequences: [1], [1] and [1, 1].",['number theory']778"Alice and Bob have received three big piles of candies as a gift. Now they want to divide these candies as fair as possible. To do this, Alice takes one pile of candies, then Bob takes one of the other two piles. The last pile is split between Alice and Bob as they want: for example, it is possible that Alice takes the whole pile, and Bob gets nothing from it.After taking the candies from the piles, if Alice has more candies than Bob, she discards some candies so that the number of candies she has is equal to the number of candies Bob has. Of course, Bob does the same if he has more candies.Alice and Bob want to have as many candies as possible, and they plan the process of dividing candies accordingly. Please calculate the maximum number of candies Alice can have after this division process (of course, Bob will have the same number of candies).You have to answer $$$q$$$ independent queries.Let's see the following example: $$$[1, 3, 4]$$$. Then Alice can choose the third pile, Bob can take the second pile, and then the only candy from the first pile goes to Bob — then Alice has $$$4$$$ candies, and Bob has $$$4$$$ candies.Another example is $$$[1, 10, 100]$$$. Then Alice can choose the second pile, Bob can choose the first pile, and candies from the third pile can be divided in such a way that Bob takes $$$54$$$ candies, and Alice takes $$$46$$$ candies. Now Bob has $$$55$$$ candies, and Alice has $$$56$$$ candies, so she has to discard one candy — and after that, she has $$$55$$$ candies too.",['math']779"Hiking club ""Up the hill"" just returned from a walk. Now they are trying to remember which hills they've just walked through.It is known that there were N stops, all on different integer heights between 1 and N kilometers (inclusive) above the sea level. On the first day they've traveled from the first stop to the second stop, on the second day they've traveled from the second to the third and so on, and on the last day they've traveled from the stop N - 1 to the stop N and successfully finished their expedition.They are trying to find out which heights were their stops located at. They have an entry in a travel journal specifying how many days did they travel up the hill, and how many days did they walk down the hill.Help them by suggesting some possible stop heights satisfying numbers from the travel journal.",[]780"Consider the array $$$a$$$ composed of all the integers in the range $$$[l, r]$$$. For example, if $$$l = 3$$$ and $$$r = 7$$$, then $$$a = [3, 4, 5, 6, 7]$$$.Given $$$l$$$, $$$r$$$, and $$$k$$$, is it possible for $$$\gcd(a)$$$ to be greater than $$$1$$$ after doing the following operation at most $$$k$$$ times?   Choose $$$2$$$ numbers from $$$a$$$.  Permanently remove one occurrence of each of them from the array.  Insert their product back into $$$a$$$. $$$\gcd(b)$$$ denotes the greatest common divisor (GCD) of the integers in $$$b$$$.","['math', 'number theory']"781"You are given three integers $$$n$$$, $$$l$$$, and $$$r$$$. You need to construct an array $$$a_1,a_2,\dots,a_n$$$ ($$$l\le a_i\le r$$$) such that $$$\gcd(i,a_i)$$$ are all distinct or report there's no solution.Here $$$\gcd(x, y)$$$ denotes the greatest common divisor (GCD) of integers $$$x$$$ and $$$y$$$.",['math']782"Ivan has n different boxes. The first of them contains some balls of n different colors.Ivan wants to play a strange game. He wants to distribute the balls into boxes in such a way that for every i (1 ≤ i ≤ n) i-th box will contain all balls with color i.In order to do this, Ivan will make some turns. Each turn he does the following:  Ivan chooses any non-empty box and takes all balls from this box;  Then Ivan chooses any k empty boxes (the box from the first step becomes empty, and Ivan is allowed to choose it), separates the balls he took on the previous step into k non-empty groups and puts each group into one of the boxes. He should put each group into a separate box. He can choose either k = 2 or k = 3. The penalty of the turn is the number of balls Ivan takes from the box during the first step of the turn. And penalty of the game is the total penalty of turns made by Ivan until he distributes all balls to corresponding boxes.Help Ivan to determine the minimum possible penalty of the game!",[]783"You are given a function $$$f$$$ written in some basic language. The function accepts an integer value, which is immediately written into some variable $$$x$$$. $$$x$$$ is an integer variable and can be assigned values from $$$0$$$ to $$$2^{32}-1$$$. The function contains three types of commands:  for $$$n$$$ — for loop;  end — every command between ""for $$$n$$$"" and corresponding ""end"" is executed $$$n$$$ times;  add — adds 1 to $$$x$$$. After the execution of these commands, value of $$$x$$$ is returned.Every ""for $$$n$$$"" is matched with ""end"", thus the function is guaranteed to be valid. ""for $$$n$$$"" can be immediately followed by ""end"".""add"" command can be outside of any for loops.Notice that ""add"" commands might overflow the value of $$$x$$$! It means that the value of $$$x$$$ becomes greater than $$$2^{32}-1$$$ after some ""add"" command. Now you run $$$f(0)$$$ and wonder if the resulting value of $$$x$$$ is correct or some overflow made it incorrect.If overflow happened then output ""OVERFLOW!!!"", otherwise print the resulting value of $$$x$$$.",[]784"Little Artem has invented a time machine! He could go anywhere in time, but all his thoughts of course are with computer science. He wants to apply this time machine to a well-known data structure: multiset.Artem wants to create a basic multiset of integers. He wants these structure to support operations of three types:  Add integer to the multiset. Note that the difference between set and multiset is that multiset may store several instances of one integer.  Remove integer from the multiset. Only one instance of this integer is removed. Artem doesn't want to handle any exceptions, so he assumes that every time remove operation is called, that integer is presented in the multiset.  Count the number of instances of the given integer that are stored in the multiset. But what about time machine? Artem doesn't simply apply operations to the multiset one by one, he now travels to different moments of time and apply his operation there. Consider the following example.  First Artem adds integer 5 to the multiset at the 1-st moment of time.  Then Artem adds integer 3 to the multiset at the moment 5.  Then Artem asks how many 5 are there in the multiset at moment 6. The answer is 1.  Then Artem returns back in time and asks how many integers 3 are there in the set at moment 4. Since 3 was added only at moment 5, the number of integers 3 at moment 4 equals to 0.  Then Artem goes back in time again and removes 5 from the multiset at moment 3.  Finally Artyom asks at moment 7 how many integers 5 are there in the set. The result is 0, since we have removed 5 at the moment 3. Note that Artem dislikes exceptions so much that he assures that after each change he makes all delete operations are applied only to element that is present in the multiset. The answer to the query of the third type is computed at the moment Artem makes the corresponding query and are not affected in any way by future changes he makes.Help Artem implement time travellers multiset.",[]785"You have three piles of candies: red, green and blue candies:  the first pile contains only red candies and there are $$$r$$$ candies in it,  the second pile contains only green candies and there are $$$g$$$ candies in it,  the third pile contains only blue candies and there are $$$b$$$ candies in it. Each day Tanya eats exactly two candies of different colors. She is free to choose the colors of eaten candies: the only restriction that she can't eat two candies of the same color in a day.Find the maximal number of days Tanya can eat candies? Each day she needs to eat exactly two candies.",['math']786"The only difference between easy and hard versions is the length of the string.You are given a string $$$s$$$ and a string $$$t$$$, both consisting only of lowercase Latin letters. It is guaranteed that $$$t$$$ can be obtained from $$$s$$$ by removing some (possibly, zero) number of characters (not necessary contiguous) from $$$s$$$ without changing order of remaining characters (in other words, it is guaranteed that $$$t$$$ is a subsequence of $$$s$$$).For example, the strings ""test"", ""tst"", ""tt"", ""et"" and """" are subsequences of the string ""test"". But the strings ""tset"", ""se"", ""contest"" are not subsequences of the string ""test"".You want to remove some substring (contiguous subsequence) from $$$s$$$ of maximum possible length such that after removing this substring $$$t$$$ will remain a subsequence of $$$s$$$.If you want to remove the substring $$$s[l;r]$$$ then the string $$$s$$$ will be transformed to $$$s_1 s_2 \dots s_{l-1} s_{r+1} s_{r+2} \dots s_{|s|-1} s_{|s|}$$$ (where $$$|s|$$$ is the length of $$$s$$$).Your task is to find the maximum possible length of the substring you can remove so that $$$t$$$ is still a subsequence of $$$s$$$.",[]787"A kindergarten teacher Natalia Pavlovna has invented a new ball game. This game not only develops the children's physique, but also teaches them how to count. The game goes as follows. Kids stand in circle. Let's agree to think of the children as numbered with numbers from 1 to n clockwise and the child number 1 is holding the ball. First the first child throws the ball to the next one clockwise, i.e. to the child number 2. Then the child number 2 throws the ball to the next but one child, i.e. to the child number 4, then the fourth child throws the ball to the child that stands two children away from him, i.e. to the child number 7, then the ball is thrown to the child who stands 3 children away from the child number 7, then the ball is thrown to the child who stands 4 children away from the last one, and so on. It should be mentioned that when a ball is thrown it may pass the beginning of the circle. For example, if n = 5, then after the third throw the child number 2 has the ball again. Overall, n - 1 throws are made, and the game ends.The problem is that not all the children get the ball during the game. If a child doesn't get the ball, he gets very upset and cries until Natalia Pavlovna gives him a candy. That's why Natalia Pavlovna asks you to help her to identify the numbers of the children who will get the ball after each throw.",[]788"Finally, a basketball court has been opened in SIS, so Demid has decided to hold a basketball exercise session. $$$2 \cdot n$$$ students have come to Demid's exercise session, and he lined up them into two rows of the same size (there are exactly $$$n$$$ people in each row). Students are numbered from $$$1$$$ to $$$n$$$ in each row in order from left to right.  Now Demid wants to choose a team to play basketball. He will choose players from left to right, and the index of each chosen player (excluding the first one taken) will be strictly greater than the index of the previously chosen player. To avoid giving preference to one of the rows, Demid chooses students in such a way that no consecutive chosen students belong to the same row. The first student can be chosen among all $$$2n$$$ students (there are no additional constraints), and a team can consist of any number of students. Demid thinks, that in order to compose a perfect team, he should choose students in such a way, that the total height of all chosen students is maximum possible. Help Demid to find the maximum possible total height of players in a team he can choose.",[]789"You have array a that contains all integers from 1 to n twice. You can arbitrary permute any numbers in a.Let number i be in positions xi, yi (xi < yi) in the permuted array a. Let's define the value di = yi - xi — the distance between the positions of the number i. Permute the numbers in array a to minimize the value of the sum .",[]790"Masha works in an advertising agency. In order to promote the new brand, she wants to conclude contracts with some bloggers. In total, Masha has connections of $$$n$$$ different bloggers. Blogger numbered $$$i$$$ has $$$a_i$$$ followers.Since Masha has a limited budget, she can only sign a contract with $$$k$$$ different bloggers. Of course, Masha wants her ad to be seen by as many people as possible. Therefore, she must hire bloggers with the maximum total number of followers.Help her, find the number of ways to select $$$k$$$ bloggers so that the total number of their followers is maximum possible. Two ways are considered different if there is at least one blogger in the first way, which is not in the second way. Masha believes that all bloggers have different followers (that is, there is no follower who would follow two different bloggers).For example, if $$$n=4$$$, $$$k=3$$$, $$$a=[1, 3, 1, 2]$$$, then Masha has two ways to select $$$3$$$ bloggers with the maximum total number of followers:   conclude contracts with bloggers with numbers $$$1$$$, $$$2$$$ and $$$4$$$. In this case, the number of followers will be equal to $$$a_1 + a_2 + a_4 = 6$$$.  conclude contracts with bloggers with numbers $$$2$$$, $$$3$$$ and $$$4$$$. In this case, the number of followers will be equal to $$$a_2 + a_3 + a_4 = 6$$$. Since the answer can be quite large, output it modulo $$$10^9+7$$$.",['math']791"You have n devices that you want to use simultaneously.The i-th device uses ai units of power per second. This usage is continuous. That is, in λ seconds, the device will use λ·ai units of power. The i-th device currently has bi units of power stored. All devices can store an arbitrary amount of power.You have a single charger that can plug to any single device. The charger will add p units of power per second to a device. This charging is continuous. That is, if you plug in a device for λ seconds, it will gain λ·p units of power. You can switch which device is charging at any arbitrary unit of time (including real numbers), and the time it takes to switch is negligible.You are wondering, what is the maximum amount of time you can use the devices until one of them hits 0 units of power.If you can use the devices indefinitely, print -1. Otherwise, print the maximum amount of time before any one device hits 0 power.",['math']792"Polycarp is sad — New Year is coming in few days but there is still no snow in his city. To bring himself New Year mood, he decided to decorate his house with some garlands.The local store introduced a new service this year, called ""Build your own garland"". So you can buy some red, green and blue lamps, provide them and the store workers will solder a single garland of them. The resulting garland will have all the lamps you provided put in a line. Moreover, no pair of lamps of the same color will be adjacent to each other in this garland!For example, if you provide $$$3$$$ red, $$$3$$$ green and $$$3$$$ blue lamps, the resulting garland can look like this: ""RGBRBGBGR"" (""RGB"" being the red, green and blue color, respectively). Note that it's ok to have lamps of the same color on the ends of the garland.However, if you provide, say, $$$1$$$ red, $$$10$$$ green and $$$2$$$ blue lamps then the store workers won't be able to build any garland of them. Any garland consisting of these lamps will have at least one pair of lamps of the same color adjacent to each other. Note that the store workers should use all the lamps you provided.So Polycarp has bought some sets of lamps and now he wants to know if the store workers can build a garland from each of them.",['math']793"You are given two strings $$$s$$$ and $$$t$$$ both of length $$$n$$$ and both consisting of lowercase Latin letters.In one move, you can choose any length $$$len$$$ from $$$1$$$ to $$$n$$$ and perform the following operation:   Choose any contiguous substring of the string $$$s$$$ of length $$$len$$$ and reverse it;  at the same time choose any contiguous substring of the string $$$t$$$ of length $$$len$$$ and reverse it as well. Note that during one move you reverse exactly one substring of the string $$$s$$$ and exactly one substring of the string $$$t$$$.Also note that borders of substrings you reverse in $$$s$$$ and in $$$t$$$ can be different, the only restriction is that you reverse the substrings of equal length. For example, if $$$len=3$$$ and $$$n=5$$$, you can reverse $$$s[1 \dots 3]$$$ and $$$t[3 \dots 5]$$$, $$$s[2 \dots 4]$$$ and $$$t[2 \dots 4]$$$, but not $$$s[1 \dots 3]$$$ and $$$t[1 \dots 2]$$$.Your task is to say if it is possible to make strings $$$s$$$ and $$$t$$$ equal after some (possibly, empty) sequence of moves.You have to answer $$$q$$$ independent test cases.",['strings']794"A permutation of length $$$n$$$ is an array $$$p=[p_1,p_2,\dots, p_n]$$$ which contains every integer from $$$1$$$ to $$$n$$$ (inclusive) exactly once. For example, $$$p=[4, 2, 6, 5, 3, 1]$$$ is a permutation of length $$$6$$$.You are given three integers $$$n$$$, $$$a$$$ and $$$b$$$, where $$$n$$$ is an even number. Print any permutation of length $$$n$$$ that the minimum among all its elements of the left half equals $$$a$$$ and the maximum among all its elements of the right half equals $$$b$$$. Print -1 if no such permutation exists.",[]795"Monocarp is playing a computer game once again. He is a wizard apprentice, who only knows a single spell. Luckily, this spell can damage the monsters.The level he's currently on contains $$$n$$$ monsters. The $$$i$$$-th of them appears $$$k_i$$$ seconds after the start of the level and has $$$h_i$$$ health points. As an additional constraint, $$$h_i \le k_i$$$ for all $$$1 \le i \le n$$$. All $$$k_i$$$ are different.Monocarp can cast the spell at moments which are positive integer amounts of second after the start of the level: $$$1, 2, 3, \dots$$$ The damage of the spell is calculated as follows. If he didn't cast the spell at the previous second, the damage is $$$1$$$. Otherwise, let the damage at the previous second be $$$x$$$. Then he can choose the damage to be either $$$x + 1$$$ or $$$1$$$. A spell uses mana: casting a spell with damage $$$x$$$ uses $$$x$$$ mana. Mana doesn't regenerate.To kill the $$$i$$$-th monster, Monocarp has to cast a spell with damage at least $$$h_i$$$ at the exact moment the monster appears, which is $$$k_i$$$.Note that Monocarp can cast the spell even when there is no monster at the current second.The mana amount required to cast the spells is the sum of mana usages for all cast spells. Calculate the least amount of mana required for Monocarp to kill all monsters.It can be shown that it's always possible to kill all monsters under the constraints of the problem.",['math']796"DZY has a sequence a, consisting of n integers.We'll call a sequence ai, ai + 1, ..., aj (1 ≤ i ≤ j ≤ n) a subsegment of the sequence a. The value (j - i + 1) denotes the length of the subsegment.Your task is to find the longest subsegment of a, such that it is possible to change at most one number (change one number to any integer you want) from the subsegment to make the subsegment strictly increasing.You only need to output the length of the subsegment you find.",[]797"There are n stone quarries in Petrograd.Each quarry owns mi dumpers (1 ≤ i ≤ n). It is known that the first dumper of the i-th quarry has xi stones in it, the second dumper has xi + 1 stones in it, the third has xi + 2, and the mi-th dumper (the last for the i-th quarry) has xi + mi - 1 stones in it.Two oligarchs play a well-known game Nim. Players take turns removing stones from dumpers. On each turn, a player can select any dumper and remove any non-zero amount of stones from it. The player who cannot take a stone loses.Your task is to find out which oligarch will win, provided that both of them play optimally. The oligarchs asked you not to reveal their names. So, let's call the one who takes the first stone «tolik» and the other one «bolik».",['games']798"A rare article in the Internet is posted without a possibility to comment it. On a Polycarp's website each article has comments feed.Each comment on Polycarp's website is a non-empty string consisting of uppercase and lowercase letters of English alphabet. Comments have tree-like structure, that means each comment except root comments (comments of the highest level) has exactly one parent comment.When Polycarp wants to save comments to his hard drive he uses the following format. Each comment he writes in the following format:   at first, the text of the comment is written;  after that the number of comments is written, for which this comment is a parent comment (i. e. the number of the replies to this comments);  after that the comments for which this comment is a parent comment are written (the writing of these comments uses the same algorithm).  All elements in this format are separated by single comma. Similarly, the comments of the first level are separated by comma.For example, if the comments look like:  then the first comment is written as ""hello,2,ok,0,bye,0"", the second is written as ""test,0"", the third comment is written as ""one,1,two,2,a,0,b,0"". The whole comments feed is written as: ""hello,2,ok,0,bye,0,test,0,one,1,two,2,a,0,b,0"". For a given comments feed in the format specified above print the comments in a different format:   at first, print a integer d — the maximum depth of nesting comments;  after that print d lines, the i-th of them corresponds to nesting level i;  for the i-th row print comments of nesting level i in the order of their appearance in the Policarp's comments feed, separated by space. ",['strings']799"While playing yet another strategy game, Mans has recruited $$$n$$$ Swedish heroes, whose powers which can be represented as an array $$$a$$$.Unfortunately, not all of those mighty heroes were created as capable as he wanted, so that he decided to do something about it. In order to accomplish his goal, he can pick two consecutive heroes, with powers $$$a_i$$$ and $$$a_{i+1}$$$, remove them and insert a hero with power $$$-(a_i+a_{i+1})$$$ back in the same position. For example if the array contains the elements $$$[5, 6, 7, 8]$$$, he can pick $$$6$$$ and $$$7$$$ and get $$$[5, -(6+7), 8] = [5, -13, 8]$$$.After he will perform this operation $$$n-1$$$ times, Mans will end up having only one hero. He wants his power to be as big as possible. What's the largest possible power he can achieve?",[]800"You are given an array $$$a$$$ of length $$$n$$$. We define the equality of the array as the number of indices $$$1 \le i \le n - 1$$$ such that $$$a_i = a_{i + 1}$$$. We are allowed to do the following operation:  Select two integers $$$i$$$ and $$$x$$$ such that $$$1 \le i \le n - 1$$$ and $$$1 \le x \le 10^9$$$. Then, set $$$a_i$$$ and $$$a_{i + 1}$$$ to be equal to $$$x$$$. Find the minimum number of operations needed such that the equality of the array is less than or equal to $$$1$$$.",[]801"A very unusual citizen lives in a far away kingdom — Dwarf Gracula. However, his unusual name is not the weirdest thing (besides, everyone long ago got used to calling him simply Dwarf Greg). What is special about Dwarf Greg — he's been living for over 200 years; besides, he lives in a crypt on an abandoned cemetery and nobody has ever seen him out in daytime. Moreover, nobody has ever seen Greg buy himself any food. That's why nobody got particularly surprised when after the infernal dragon's tragic death cattle continued to disappear from fields. The people in the neighborhood were long sure that the harmless dragon was never responsible for disappearing cattle (considering that the dragon used to be sincere about his vegetarian views). But even that's not the worst part of the whole story.The worst part is that merely several minutes ago Dwarf Greg in some unintelligible way got inside your house and asked you to help him solve a problem. The point is that a short time ago Greg decided to order a new coffin (knowing his peculiar character, you are not surprised at all). But the problem is: a very long in both directions L-shaped corridor leads to Greg's crypt, and you can't drag just any coffin through that corridor. That's why he asked you to help.  You've formalized the task on a plane like this: let the corridor's width before and after the turn be equal to a and b correspondingly (see the picture). The corridor turns directly at a right angle, the coffin is a rectangle whose length and width are equal to l and w (l ≥ w) correspondingly. Dwarf Greg has already determined the coffin's length (l), which is based on his height; your task is to determine the coffin's maximally possible width (w), at which it can be brought to the crypt. Besides, due to its large mass (pure marble!) the coffin is equipped with rotating wheels; therefore it is impossible to lift it off the ground, however, arbitrary moves and rotations of the coffin in the plane become possible. The coffin may be rotated arbitrarily just before you drag it into crypt and move through the corridor.Greg promised that if you help him, he will grant you immortality (I wonder how?). And if you don't, well... trust me, you don't want to know what happens if you don't help him...",['geometry']802"Lesha plays the recently published new version of the legendary game hacknet. In this version character skill mechanism was introduced. Now, each player character has exactly n skills. Each skill is represented by a non-negative integer ai — the current skill level. All skills have the same maximum level A.Along with the skills, global ranking of all players was added. Players are ranked according to the so-called Force. The Force of a player is the sum of the following values:  The number of skills that a character has perfected (i.e., such that ai = A), multiplied by coefficient cf. The minimum skill level among all skills (min ai), multiplied by coefficient cm. Now Lesha has m hacknetian currency units, which he is willing to spend. Each currency unit can increase the current level of any skill by 1 (if it's not equal to A yet). Help him spend his money in order to achieve the maximum possible value of the Force.",[]803"Given an integer $$$n$$$, find any array $$$a$$$ of $$$n$$$ distinct nonnegative integers less than $$$2^{31}$$$ such that the bitwise XOR of the elements on odd indices equals the bitwise XOR of the elements on even indices.",[]804"Dark is going to attend Motarack's birthday. Dark decided that the gift he is going to give to Motarack is an array $$$a$$$ of $$$n$$$ non-negative integers.Dark created that array $$$1000$$$ years ago, so some elements in that array disappeared. Dark knows that Motarack hates to see an array that has two adjacent elements with a high absolute difference between them. He doesn't have much time so he wants to choose an integer $$$k$$$ ($$$0 \leq k \leq 10^{9}$$$) and replaces all missing elements in the array $$$a$$$ with $$$k$$$.Let $$$m$$$ be the maximum absolute difference between all adjacent elements (i.e. the maximum value of $$$|a_i - a_{i+1}|$$$ for all $$$1 \leq i \leq n - 1$$$) in the array $$$a$$$ after Dark replaces all missing elements with $$$k$$$.Dark should choose an integer $$$k$$$ so that $$$m$$$ is minimized. Can you help him?",[]805"You are given an array $$$a$$$ consisting of $$$n$$$ integers $$$a_1, a_2, \dots, a_n$$$. You want to split it into exactly $$$k$$$ non-empty non-intersecting subsegments such that each subsegment has odd sum (i. e. for each subsegment, the sum of all elements that belong to this subsegment is odd). It is impossible to rearrange (shuffle) the elements of a given array. Each of the $$$n$$$ elements of the array $$$a$$$ must belong to exactly one of the $$$k$$$ subsegments.Let's see some examples of dividing the array of length $$$5$$$ into $$$3$$$ subsegments (not necessarily with odd sums): $$$[1, 2, 3, 4, 5]$$$ is the initial array, then all possible ways to divide it into $$$3$$$ non-empty non-intersecting subsegments are described below:  $$$[1], [2], [3, 4, 5]$$$;  $$$[1], [2, 3], [4, 5]$$$;  $$$[1], [2, 3, 4], [5]$$$;  $$$[1, 2], [3], [4, 5]$$$;  $$$[1, 2], [3, 4], [5]$$$;  $$$[1, 2, 3], [4], [5]$$$. Of course, it can be impossible to divide the initial array into exactly $$$k$$$ subsegments in such a way that each of them will have odd sum of elements. In this case print ""NO"". Otherwise, print ""YES"" and any possible division of the array. See the output format for the detailed explanation.You have to answer $$$q$$$ independent queries.",['math']806"The Olympic Games in Bercouver are in full swing now. Here everyone has their own objectives: sportsmen compete for medals, and sport commentators compete for more convenient positions to give a running commentary. Today the main sport events take place at three round stadiums, and the commentator's objective is to choose the best point of observation, that is to say the point from where all the three stadiums can be observed. As all the sport competitions are of the same importance, the stadiums should be observed at the same angle. If the number of points meeting the conditions is more than one, the point with the maximum angle of observation is prefered. Would you, please, help the famous Berland commentator G. Berniev to find the best point of observation. It should be noted, that the stadiums do not hide each other, the commentator can easily see one stadium through the other.",['geometry']807"Xenia the horse breeder has n (n > 1) horses that stand in a row. Each horse has its own unique number. Initially, the i-th left horse has number i. That is, the sequence of numbers of horses in a row looks as follows (from left to right): 1, 2, 3, ..., n.Xenia trains horses before the performance. During the practice sessions, she consistently gives them commands. Each command is a pair of numbers l, r (1 ≤ l < r ≤ n). The command l, r means that the horses that are on the l-th, (l + 1)-th, (l + 2)-th, ..., r-th places from the left must be rearranged. The horses that initially stand on the l-th and r-th places will swap. The horses on the (l + 1)-th and (r - 1)-th places will swap. The horses on the (l + 2)-th and (r - 2)-th places will swap and so on. In other words, the horses that were on the segment [l, r] change their order to the reverse one.For example, if Xenia commanded l = 2, r = 5, and the sequence of numbers of horses before the command looked as (2, 1, 3, 4, 5, 6), then after the command the sequence will be (2, 5, 4, 3, 1, 6).We know that during the practice Xenia gave at most three commands of the described form. You have got the final sequence of numbers of horses by the end of the practice. Find what commands Xenia gave during the practice. Note that you do not need to minimize the number of commands in the solution, find any valid sequence of at most three commands.",[]808"There are $$$n$$$ points and $$$m$$$ segments on the coordinate line. The initial coordinate of the $$$i$$$-th point is $$$a_i$$$. The endpoints of the $$$j$$$-th segment are $$$l_j$$$ and $$$r_j$$$ — left and right endpoints, respectively.You can move the points. In one move you can move any point from its current coordinate $$$x$$$ to the coordinate $$$x - 1$$$ or the coordinate $$$x + 1$$$. The cost of this move is $$$1$$$.You should move the points in such a way that each segment is visited by at least one point. A point visits the segment $$$[l, r]$$$ if there is a moment when its coordinate was on the segment $$$[l, r]$$$ (including endpoints).You should find the minimal possible total cost of all moves such that all segments are visited.",[]809"To confuse the opponents, the Galactic Empire represents fractions in an unusual format. The fractions are represented as two sets of integers. The product of numbers from the first set gives the fraction numerator, the product of numbers from the second set gives the fraction denominator. However, it turned out that the programs that work with fractions in this representations aren't complete, they lack supporting the operation of reducing fractions. Implement this operation and the Empire won't forget you.","['math', 'number theory']"810"The Little Elephant very much loves sums on intervals.This time he has a pair of integers l and r (l ≤ r). The Little Elephant has to find the number of such integers x (l ≤ x ≤ r), that the first digit of integer x equals the last one (in decimal notation). For example, such numbers as 101, 477474 or 9 will be included in the answer and 47, 253 or 1020 will not.Help him and count the number of described numbers x for a given pair l and r.",['math']811"Burenka and Tonya are playing an old Buryat game with a chip on a board of $$$n \times m$$$ cells.At the beginning of the game, the chip is located in the lower left corner of the board. In one move, the player can move the chip to the right or up by any odd number of cells (but you cannot move the chip both to the right and up in one move). The one who cannot make a move loses.Burenka makes the first move, the players take turns. Burenka really wants to win the game, but she is too lazy to come up with a strategy, so you are invited to solve the difficult task of finding it. Name the winner of the game (it is believed that Burenka and Tonya are masters of playing with chips, so they always move in the optimal way).    Chip's starting cell is green, the only cell from which chip can't move is red. if the chip is in the yellow cell, then blue cells are all options to move the chip in one move. ","['math', 'games']"812"An L-shape is a figure on gridded paper that looks like the first four pictures below. An L-shape contains exactly three shaded cells (denoted by *), which can be rotated in any way.  You are given a rectangular grid. Determine if it contains L-shapes only, where L-shapes can't touch an edge or corner. More formally:   Each shaded cell in the grid is part of exactly one L-shape, and  no two L-shapes are adjacent by edge or corner. For example, the last two grids in the picture above do not satisfy the condition because the two L-shapes touch by corner and edge, respectively.",[]813"Sakuzyo - ImprintingA.R.C. Markland-N is a tall building with $$$n$$$ floors numbered from $$$1$$$ to $$$n$$$. Between each two adjacent floors in the building, there is a staircase connecting them.It's lunchtime for our sensei Colin ""ConneR"" Neumann Jr, and he's planning for a location to enjoy his meal.ConneR's office is at floor $$$s$$$ of the building. On each floor (including floor $$$s$$$, of course), there is a restaurant offering meals. However, due to renovations being in progress, $$$k$$$ of the restaurants are currently closed, and as a result, ConneR can't enjoy his lunch there.CooneR wants to reach a restaurant as quickly as possible to save time. What is the minimum number of staircases he needs to walk to reach a closest currently open restaurant.Please answer him quickly, and you might earn his praise and even enjoy the lunch with him in the elegant Neumanns' way!",[]814"This is a simplified version of the problem B2. Perhaps you should read the problem B2 before you start solving B1.Paul and Mary have a favorite string $$$s$$$ which consists of lowercase letters of the Latin alphabet. They want to paint it using pieces of chalk of two colors: red and green. Let's call a coloring of a string wonderful if the following conditions are met:  each letter of the string is either painted in exactly one color (red or green) or isn't painted;  each two letters which are painted in the same color are different;  the number of letters painted in red is equal to the number of letters painted in green;  the number of painted letters of this coloring is maximum among all colorings of the string which meet the first three conditions. E. g. consider a string $$$s$$$ equal to ""kzaaa"". One of the wonderful colorings of the string is shown in the figure.    The example of a wonderful coloring of the string ""kzaaa"". Paul and Mary want to learn by themselves how to find a wonderful coloring of the string. But they are very young, so they need a hint. Help them find $$$k$$$ — the number of red (or green, these numbers are equal) letters in a wonderful coloring.",['strings']815"Polycarp lives on a coordinate line at the point $$$x = 0$$$. He goes to his friend that lives at the point $$$x = a$$$. Polycarp can move only from left to right, he can pass one unit of length each second.Now it's raining, so some segments of his way are in the rain. Formally, it's raining on $$$n$$$ non-intersecting segments, the $$$i$$$-th segment which is in the rain is represented as $$$[l_i, r_i]$$$ ($$$0 \le l_i < r_i \le a$$$).There are $$$m$$$ umbrellas lying on the line, the $$$i$$$-th umbrella is located at point $$$x_i$$$ ($$$0 \le x_i \le a$$$) and has weight $$$p_i$$$. When Polycarp begins his journey, he doesn't have any umbrellas.During his journey from $$$x = 0$$$ to $$$x = a$$$ Polycarp can pick up and throw away umbrellas. Polycarp picks up and throws down any umbrella instantly. He can carry any number of umbrellas at any moment of time. Because Polycarp doesn't want to get wet, he must carry at least one umbrella while he moves from $$$x$$$ to $$$x + 1$$$ if a segment $$$[x, x + 1]$$$ is in the rain (i.e. if there exists some $$$i$$$ such that $$$l_i \le x$$$ and $$$x + 1 \le r_i$$$).The condition above is the only requirement. For example, it is possible to go without any umbrellas to a point where some rain segment starts, pick up an umbrella at this point and move along with an umbrella. Polycarp can swap umbrellas while he is in the rain.Each unit of length passed increases Polycarp's fatigue by the sum of the weights of umbrellas he carries while moving.Can Polycarp make his way from point $$$x = 0$$$ to point $$$x = a$$$? If yes, find the minimum total fatigue after reaching $$$x = a$$$, if Polycarp picks up and throws away umbrellas optimally.",[]816"It's hard times now. Today Petya needs to score 100 points on Informatics exam. The tasks seem easy to Petya, but he thinks he lacks time to finish them all, so he asks you to help with one..There is a glob pattern in the statements (a string consisting of lowercase English letters, characters ""?"" and ""*""). It is known that character ""*"" occurs no more than once in the pattern.Also, n query strings are given, it is required to determine for each of them if the pattern matches it or not.Everything seemed easy to Petya, but then he discovered that the special pattern characters differ from their usual meaning.A pattern matches a string if it is possible to replace each character ""?"" with one good lowercase English letter, and the character ""*"" (if there is one) with any, including empty, string of bad lowercase English letters, so that the resulting string is the same as the given string.The good letters are given to Petya. All the others are bad.",['strings']817"Polycarp loves geometric progressions very much. Since he was only three years old, he loves only the progressions of length three. He also has a favorite integer k and a sequence a, consisting of n integers.He wants to know how many subsequences of length three can be selected from a, so that they form a geometric progression with common ratio k.A subsequence of length three is a combination of three such indexes i1, i2, i3, that 1 ≤ i1 < i2 < i3 ≤ n. That is, a subsequence of length three are such groups of three elements that are not necessarily consecutive in the sequence, but their indexes are strictly increasing.A geometric progression with common ratio k is a sequence of numbers of the form b·k0, b·k1, ..., b·kr - 1.Polycarp is only three years old, so he can not calculate this number himself. Help him to do it.",[]818"You have a sequence of $$$n$$$ colored blocks. The color of the $$$i$$$-th block is $$$c_i$$$, an integer between $$$1$$$ and $$$n$$$.You will place the blocks down in sequence on an infinite coordinate grid in the following way.   Initially, you place block $$$1$$$ at $$$(0, 0)$$$.  For $$$2 \le i \le n$$$, if the $$$(i - 1)$$$-th block is placed at position $$$(x, y)$$$, then the $$$i$$$-th block can be placed at one of positions $$$(x + 1, y)$$$, $$$(x - 1, y)$$$, $$$(x, y + 1)$$$ (but not at position $$$(x, y - 1)$$$), as long no previous block was placed at that position. A tower is formed by $$$s$$$ blocks such that they are placed at positions $$$(x, y), (x, y + 1), \ldots, (x, y + s - 1)$$$ for some position $$$(x, y)$$$ and integer $$$s$$$. The size of the tower is $$$s$$$, the number of blocks in it. A tower of color $$$r$$$ is a tower such that all blocks in it have the color $$$r$$$.For each color $$$r$$$ from $$$1$$$ to $$$n$$$, solve the following problem independently:   Find the maximum size of a tower of color $$$r$$$ that you can form by placing down the blocks according to the rules. ",['math']819"This problem is a version of problem D from the same contest with some additional constraints and tasks.There are $$$n$$$ candies in a candy box. The type of the $$$i$$$-th candy is $$$a_i$$$ ($$$1 \le a_i \le n$$$). You have to prepare a gift using some of these candies with the following restriction: the numbers of candies of each type presented in a gift should be all distinct (i. e. for example, a gift having two candies of type $$$1$$$ and two candies of type $$$2$$$ is bad).It is possible that multiple types of candies are completely absent from the gift. It is also possible that not all candies of some types will be taken to a gift.You really like some of the candies and don't want to include them into the gift, but you want to eat them yourself instead. For each candy, a number $$$f_i$$$ is given, which is equal to $$$0$$$ if you really want to keep $$$i$$$-th candy for yourself, or $$$1$$$ if you don't mind including it into your gift. It is possible that two candies of the same type have different values of $$$f_i$$$.You want your gift to be as large as possible, but you don't want to include too many of the candies you want to eat into the gift. So, you want to calculate the maximum possible number of candies that can be included into a gift, and among all ways to choose maximum number of candies, you want to maximize the number of candies having $$$f_i = 1$$$ in your gift.You have to answer $$$q$$$ independent queries.If you are Python programmer, consider using PyPy instead of Python when you submit your code.",[]820"Emily's birthday is next week and Jack has decided to buy a present for her. He knows she loves books so he goes to the local bookshop, where there are n books on sale from one of m genres.In the bookshop, Jack decides to buy two books of different genres.Based on the genre of books on sale in the shop, find the number of options available to Jack for choosing two books of different genres for Emily. Options are considered different if they differ in at least one book.The books are given by indices of their genres. The genres are numbered from 1 to m.",[]821"Anya has bought a new smartphone that uses Berdroid operating system. The smartphone menu has exactly n applications, each application has its own icon. The icons are located on different screens, one screen contains k icons. The icons from the first to the k-th one are located on the first screen, from the (k + 1)-th to the 2k-th ones are on the second screen and so on (the last screen may be partially empty).Initially the smartphone menu is showing the screen number 1. To launch the application with the icon located on the screen t, Anya needs to make the following gestures: first she scrolls to the required screen number t, by making t - 1 gestures (if the icon is on the screen t), and then make another gesture — press the icon of the required application exactly once to launch it.After the application is launched, the menu returns to the first screen. That is, to launch the next application you need to scroll through the menu again starting from the screen number 1.All applications are numbered from 1 to n. We know a certain order in which the icons of the applications are located in the menu at the beginning, but it changes as long as you use the operating system. Berdroid is intelligent system, so it changes the order of the icons by moving the more frequently used icons to the beginning of the list. Formally, right after an application is launched, Berdroid swaps the application icon and the icon of a preceding application (that is, the icon of an application on the position that is smaller by one in the order of menu). The preceding icon may possibly be located on the adjacent screen. The only exception is when the icon of the launched application already occupies the first place, in this case the icon arrangement doesn't change.Anya has planned the order in which she will launch applications. How many gestures should Anya make to launch the applications in the planned order? Note that one application may be launched multiple times.",[]822"Guy-Manuel and Thomas have an array $$$a$$$ of $$$n$$$ integers [$$$a_1, a_2, \dots, a_n$$$]. In one step they can add $$$1$$$ to any element of the array. Formally, in one step they can choose any integer index $$$i$$$ ($$$1 \le i \le n$$$) and do $$$a_i := a_i + 1$$$.If either the sum or the product of all elements in the array is equal to zero, Guy-Manuel and Thomas do not mind to do this operation one more time.What is the minimum number of steps they need to do to make both the sum and the product of all elements in the array different from zero? Formally, find the minimum number of steps to make $$$a_1 + a_2 +$$$ $$$\dots$$$ $$$+ a_n \ne 0$$$ and $$$a_1 \cdot a_2 \cdot$$$ $$$\dots$$$ $$$\cdot a_n \ne 0$$$.",['math']823"As we all know, Max is the best video game player among her friends. Her friends were so jealous of hers, that they created an actual game just to prove that she's not the best at games. The game is played on a directed acyclic graph (a DAG) with n vertices and m edges. There's a character written on each edge, a lowercase English letter.  Max and Lucas are playing the game. Max goes first, then Lucas, then Max again and so on. Each player has a marble, initially located at some vertex. Each player in his/her turn should move his/her marble along some edge (a player can move the marble from vertex v to vertex u if there's an outgoing edge from v to u). If the player moves his/her marble from vertex v to vertex u, the ""character"" of that round is the character written on the edge from v to u. There's one additional rule; the ASCII code of character of round i should be greater than or equal to the ASCII code of character of round i - 1 (for i > 1). The rounds are numbered for both players together, i. e. Max goes in odd numbers, Lucas goes in even numbers. The player that can't make a move loses the game. The marbles may be at the same vertex at the same time.Since the game could take a while and Lucas and Max have to focus on finding Dart, they don't have time to play. So they asked you, if they both play optimally, who wins the game?You have to determine the winner of the game for all initial positions of the marbles.","['graphs', 'games']"824"You found a painting on a canvas of size $$$n \times m$$$. The canvas can be represented as a grid with $$$n$$$ rows and $$$m$$$ columns. Each cell has some color. Cell $$$(i, j)$$$ has color $$$c_{i,j}$$$.Near the painting you also found a brush in the shape of a $$$2 \times 2$$$ square, so the canvas was surely painted in the following way: initially, no cell was painted. Then, the following painting operation has been performed some number of times:  Choose two integers $$$i$$$ and $$$j$$$ ($$$1 \le i < n$$$, $$$1 \le j < m$$$) and some color $$$k$$$ ($$$1 \le k \le nm$$$).  Paint cells $$$(i, j)$$$, $$$(i + 1, j)$$$, $$$(i, j + 1)$$$, $$$(i + 1, j + 1)$$$ in color $$$k$$$. All cells must be painted at least once. A cell can be painted multiple times. In this case, its final color will be the last one.Find any sequence of at most $$$nm$$$ operations that could have led to the painting you found or state that it's impossible.",[]825"Karen has just arrived at school, and she has a math test today!  The test is about basic addition and subtraction. Unfortunately, the teachers were too busy writing tasks for Codeforces rounds, and had no time to make an actual test. So, they just put one question in the test that is worth all the points.There are n integers written on a row. Karen must alternately add and subtract each pair of adjacent integers, and write down the sums or differences on the next row. She must repeat this process on the values on the next row, and so on, until only one integer remains. The first operation should be addition.Note that, if she ended the previous row by adding the integers, she should start the next row by subtracting, and vice versa.The teachers will simply look at the last integer, and then if it is correct, Karen gets a perfect score, otherwise, she gets a zero for the test.Karen has studied well for this test, but she is scared that she might make a mistake somewhere and it will cause her final answer to be wrong. If the process is followed, what number can she expect to be written on the last row?Since this number can be quite large, output only the non-negative remainder after dividing it by 109 + 7.",['math']826"You are asked to watch your nephew who likes to play with toy blocks in a strange way.He has $$$n$$$ boxes and the $$$i$$$-th box has $$$a_i$$$ blocks. His game consists of two steps:   he chooses an arbitrary box $$$i$$$;  he tries to move all blocks from the $$$i$$$-th box to other boxes.  If he can make the same number of blocks in each of $$$n - 1$$$ other boxes then he will be happy, otherwise, will be sad. Note that your nephew can only move the blocks from the chosen box to the other boxes; he cannot move blocks from the other boxes.You don't want to make your nephew sad, so you decided to put several extra blocks into some boxes in such a way that no matter which box $$$i$$$ he chooses he won't be sad. What is the minimum number of extra blocks you need to put?",['math']827"Jack decides to invite Emma out for a dinner. Jack is a modest student, he doesn't want to go to an expensive restaurant. Emma is a girl with high taste, she prefers elite places.Munhattan consists of n streets and m avenues. There is exactly one restaurant on the intersection of each street and avenue. The streets are numbered with integers from 1 to n and the avenues are numbered with integers from 1 to m. The cost of dinner in the restaurant at the intersection of the i-th street and the j-th avenue is cij.Jack and Emma decide to choose the restaurant in the following way. Firstly Emma chooses the street to dinner and then Jack chooses the avenue. Emma and Jack makes their choice optimally: Emma wants to maximize the cost of the dinner, Jack wants to minimize it. Emma takes into account that Jack wants to minimize the cost of the dinner. Find the cost of the dinner for the couple in love.",['games']828"During her tantrums the princess usually smashes some collectable porcelain. Every furious shriek is accompanied with one item smashed.The collection of porcelain is arranged neatly on n shelves. Within each shelf the items are placed in one row, so that one can access only the outermost items — the leftmost or the rightmost item, not the ones in the middle of the shelf. Once an item is taken, the next item on that side of the shelf can be accessed (see example). Once an item is taken, it can't be returned to the shelves.You are given the values of all items. Your task is to find the maximal damage the princess' tantrum of m shrieks can inflict on the collection of porcelain.",[]829"The pandemic is upon us, and the world is in shortage of the most important resource: toilet paper. As one of the best prepared nations for this crisis, BubbleLand promised to help all other world nations with this valuable resource. To do that, the country will send airplanes to other countries carrying toilet paper.In BubbleLand, there are $$$N$$$ toilet paper factories, and $$$N$$$ airports. Because of how much it takes to build a road, and of course legal issues, every factory must send paper to only one airport, and every airport can only take toilet paper from one factory.Also, a road can't be built between all airport-factory pairs, again because of legal issues. Every possible road has number $$$d$$$ given, number of days it takes to build that road.Your job is to choose $$$N$$$ factory-airport pairs, such that if the country starts building all roads at the same time, it takes the least amount of days to complete them.",['graphs']830"Polycarp was dismantling his attic and found an old floppy drive on it. A round disc was inserted into the drive with $$$n$$$ integers written on it.Polycarp wrote the numbers from the disk into the $$$a$$$ array. It turned out that the drive works according to the following algorithm:   the drive takes one positive number $$$x$$$ as input and puts a pointer to the first element of the $$$a$$$ array;  after that, the drive starts rotating the disk, every second moving the pointer to the next element, counting the sum of all the elements that have been under the pointer. Since the disk is round, in the $$$a$$$ array, the last element is again followed by the first one;  as soon as the sum is at least $$$x$$$, the drive will shut down. Polycarp wants to learn more about the operation of the drive, but he has absolutely no free time. So he asked you $$$m$$$ questions. To answer the $$$i$$$-th of them, you need to find how many seconds the drive will work if you give it $$$x_i$$$ as input. Please note that in some cases the drive can work infinitely.For example, if $$$n=3, m=3$$$, $$$a=[1, -3, 4]$$$ and $$$x=[1, 5, 2]$$$, then the answers to the questions are as follows:   the answer to the first query is $$$0$$$ because the drive initially points to the first item and the initial sum is $$$1$$$.  the answer to the second query is $$$6$$$, the drive will spin the disk completely twice and the amount becomes $$$1+(-3)+4+1+(-3)+4+1=5$$$.  the answer to the third query is $$$2$$$, the amount is $$$1+(-3)+4=2$$$.  ",['math']831"Learn, learn and learn again — Valera has to do this every day. He is studying at mathematical school, where math is the main discipline. The mathematics teacher loves her discipline very much and tries to cultivate this love in children. That's why she always gives her students large and difficult homework. Despite that Valera is one of the best students, he failed to manage with the new homework. That's why he asks for your help. He has the following task. A sequence of n numbers is given. A prefix of a sequence is the part of the sequence (possibly empty), taken from the start of the sequence. A suffix of a sequence is the part of the sequence (possibly empty), taken from the end of the sequence. It is allowed to sequentially make two operations with the sequence. The first operation is to take some prefix of the sequence and multiply all numbers in this prefix by  - 1. The second operation is to take some suffix and multiply all numbers in it by  - 1. The chosen prefix and suffix may intersect. What is the maximum total sum of the sequence that can be obtained by applying the described operations?",[]832"Two semifinals have just been in the running tournament. Each semifinal had n participants. There are n participants advancing to the finals, they are chosen as follows: from each semifinal, we choose k people (0 ≤ 2k ≤ n) who showed the best result in their semifinals and all other places in the finals go to the people who haven't ranked in the top k in their semifinal but got to the n - 2k of the best among the others.The tournament organizers hasn't yet determined the k value, so the participants want to know who else has any chance to get to the finals and who can go home.",[]833You are given a connected undirected graph consisting of $$$n$$$ vertices and $$$m$$$ edges. There are no self-loops or multiple edges in the given graph.You have to direct its edges in such a way that the obtained directed graph does not contain any paths of length two or greater (where the length of path is denoted as the number of traversed edges).,['graphs']834"In Arcady's garden there grows a peculiar apple-tree that fruits one time per year. Its peculiarity can be explained in following way: there are n inflorescences, numbered from 1 to n. Inflorescence number 1 is situated near base of tree and any other inflorescence with number i (i > 1) is situated at the top of branch, which bottom is pi-th inflorescence and pi < i.Once tree starts fruiting, there appears exactly one apple in each inflorescence. The same moment as apples appear, they start to roll down along branches to the very base of tree. Each second all apples, except ones in first inflorescence simultaneously roll down one branch closer to tree base, e.g. apple in a-th inflorescence gets to pa-th inflorescence. Apples that end up in first inflorescence are gathered by Arcady in exactly the same moment. Second peculiarity of this tree is that once two apples are in same inflorescence they annihilate. This happens with each pair of apples, e.g. if there are 5 apples in same inflorescence in same time, only one will not be annihilated and if there are 8 apples, all apples will be annihilated. Thus, there can be no more than one apple in each inflorescence in each moment of time.Help Arcady with counting number of apples he will be able to collect from first inflorescence during one harvest.","['graphs', 'trees']"835"Suppose you are given a string $$$s$$$ of length $$$n$$$ consisting of lowercase English letters. You need to compress it using the smallest possible number of coins.To compress the string, you have to represent $$$s$$$ as a concatenation of several non-empty strings: $$$s = t_{1} t_{2} \ldots t_{k}$$$. The $$$i$$$-th of these strings should be encoded with one of the two ways:  if $$$|t_{i}| = 1$$$, meaning that the current string consists of a single character, you can encode it paying $$$a$$$ coins;  if $$$t_{i}$$$ is a substring of $$$t_{1} t_{2} \ldots t_{i - 1}$$$, then you can encode it paying $$$b$$$ coins. A string $$$x$$$ is a substring of a string $$$y$$$ if $$$x$$$ can be obtained from $$$y$$$ by deletion of several (possibly, zero or all) characters from the beginning and several (possibly, zero or all) characters from the end.So your task is to calculate the minimum possible number of coins you need to spend in order to compress the given string $$$s$$$.",['strings']836"Highway 201 is the most busy street in Rockport. Traffic cars cause a lot of hindrances to races, especially when there are a lot of them. The track which passes through this highway can be divided into $$$n$$$ sub-tracks. You are given an array $$$a$$$ where $$$a_i$$$ represents the number of traffic cars in the $$$i$$$-th sub-track. You define the inconvenience of the track as $$$\sum\limits_{i=1}^{n} \sum\limits_{j=i+1}^{n} \lvert a_i-a_j\rvert$$$, where $$$|x|$$$ is the absolute value of $$$x$$$. You can perform the following operation any (possibly zero) number of times: choose a traffic car and move it from its current sub-track to any other sub-track.Find the minimum inconvenience you can achieve.",['math']837"Masha wants to open her own bakery and bake muffins in one of the n cities numbered from 1 to n. There are m bidirectional roads, each of whose connects some pair of cities.To bake muffins in her bakery, Masha needs to establish flour supply from some storage. There are only k storages, located in different cities numbered a1, a2, ..., ak.Unforunately the law of the country Masha lives in prohibits opening bakery in any of the cities which has storage located in it. She can open it only in one of another n - k cities, and, of course, flour delivery should be paid — for every kilometer of path between storage and bakery Masha should pay 1 ruble.Formally, Masha will pay x roubles, if she will open the bakery in some city b (ai ≠ b for every 1 ≤ i ≤ k) and choose a storage in some city s (s = aj for some 1 ≤ j ≤ k) and b and s are connected by some path of roads of summary length x (if there are more than one path, Masha is able to choose which of them should be used).Masha is very thrifty and rational. She is interested in a city, where she can open her bakery (and choose one of k storages and one of the paths between city with bakery and city with storage) and pay minimum possible amount of rubles for flour delivery. Please help Masha find this amount.",['graphs']838"Black is gifted with a Divine array $$$a$$$ consisting of $$$n$$$ ($$$1 \le n \le 2000$$$) integers. Each position in $$$a$$$ has an initial value. After shouting a curse over the array, it becomes angry and starts an unstoppable transformation.The transformation consists of infinite steps. Array $$$a$$$ changes at the $$$i$$$-th step in the following way: for every position $$$j$$$, $$$a_j$$$ becomes equal to the number of occurrences of $$$a_j$$$ in $$$a$$$ before starting this step.Here is an example to help you understand the process better:  Initial array:$$$2$$$ $$$1$$$ $$$1$$$ $$$4$$$ $$$3$$$ $$$1$$$ $$$2$$$After the $$$1$$$-st step:$$$2$$$ $$$3$$$ $$$3$$$ $$$1$$$ $$$1$$$ $$$3$$$ $$$2$$$After the $$$2$$$-nd step:$$$2$$$ $$$3$$$ $$$3$$$ $$$2$$$ $$$2$$$ $$$3$$$ $$$2$$$After the $$$3$$$-rd step:$$$4$$$ $$$3$$$ $$$3$$$ $$$4$$$ $$$4$$$ $$$3$$$ $$$4$$$...... In the initial array, we had two $$$2$$$-s, three $$$1$$$-s, only one $$$4$$$ and only one $$$3$$$, so after the first step, each element became equal to the number of its occurrences in the initial array: all twos changed to $$$2$$$, all ones changed to $$$3$$$, four changed to $$$1$$$ and three changed to $$$1$$$.The transformation steps continue forever.You have to process $$$q$$$ queries: in each query, Black is curious to know the value of $$$a_x$$$ after the $$$k$$$-th step of transformation.",[]839"You are given an array $$$a$$$ consisting of $$$n$$$ integers $$$a_1, a_2, \dots, a_n$$$.Your problem is to find such pair of indices $$$i, j$$$ ($$$1 \le i < j \le n$$$) that $$$lcm(a_i, a_j)$$$ is minimum possible.$$$lcm(x, y)$$$ is the least common multiple of $$$x$$$ and $$$y$$$ (minimum positive number such that both $$$x$$$ and $$$y$$$ are divisors of this number).","['math', 'number theory']"840"You are fighting with Zmei Gorynich — a ferocious monster from Slavic myths, a huge dragon-like reptile with multiple heads!   Initially Zmei Gorynich has $$$x$$$ heads. You can deal $$$n$$$ types of blows. If you deal a blow of the $$$i$$$-th type, you decrease the number of Gorynich's heads by $$$min(d_i, curX)$$$, there $$$curX$$$ is the current number of heads. But if after this blow Zmei Gorynich has at least one head, he grows $$$h_i$$$ new heads. If $$$curX = 0$$$ then Gorynich is defeated. You can deal each blow any number of times, in any order.For example, if $$$curX = 10$$$, $$$d = 7$$$, $$$h = 10$$$ then the number of heads changes to $$$13$$$ (you cut $$$7$$$ heads off, but then Zmei grows $$$10$$$ new ones), but if $$$curX = 10$$$, $$$d = 11$$$, $$$h = 100$$$ then number of heads changes to $$$0$$$ and Zmei Gorynich is considered defeated.Calculate the minimum number of blows to defeat Zmei Gorynich!You have to answer $$$t$$$ independent queries.",['math']841"Pak Chanek is participating in a lemper cooking competition. In the competition, Pak Chanek has to cook lempers with $$$N$$$ stoves that are arranged sequentially from stove $$$1$$$ to stove $$$N$$$. Initially, stove $$$i$$$ has a temperature of $$$A_i$$$ degrees. A stove can have a negative temperature.Pak Chanek realises that, in order for his lempers to be cooked, he needs to keep the temperature of each stove at a non-negative value. To make it happen, Pak Chanek can do zero or more operations. In one operation, Pak Chanek chooses one stove $$$i$$$ with $$$2 \leq i \leq N-1$$$, then:  changes the temperature of stove $$$i-1$$$ into $$$A_{i-1} := A_{i-1} + A_{i}$$$,  changes the temperature of stove $$$i+1$$$ into $$$A_{i+1} := A_{i+1} + A_{i}$$$, and  changes the temperature of stove $$$i$$$ into $$$A_i := -A_i$$$. Pak Chanek wants to know the minimum number of operations he needs to do such that the temperatures of all stoves are at non-negative values. Help Pak Chanek by telling him the minimum number of operations needed or by reporting if it is not possible to do.",[]842" Walking along a riverside, Mino silently takes a note of something.""Time,"" Mino thinks aloud.""What?""""Time and tide wait for no man,"" explains Mino. ""My name, taken from the river, always reminds me of this.""""And what are you recording?""""You see it, tide. Everything has its own period, and I think I've figured out this one,"" says Mino with confidence.Doubtfully, Kanno peeks at Mino's records. The records are expressed as a string $$$s$$$ of characters '0', '1' and '.', where '0' denotes a low tide, '1' denotes a high tide, and '.' denotes an unknown one (either high or low).You are to help Mino determine whether it's possible that after replacing each '.' independently with '0' or '1', a given integer $$$p$$$ is not a period of the resulting string. In case the answer is yes, please also show such a replacement to Mino.In this problem, a positive integer $$$p$$$ is considered a period of string $$$s$$$, if for all $$$1 \leq i \leq \lvert s \rvert - p$$$, the $$$i$$$-th and $$$(i + p)$$$-th characters of $$$s$$$ are the same. Here $$$\lvert s \rvert$$$ is the length of $$$s$$$.",['strings']843"You are given an integer $$$n$$$. You have to apply $$$m$$$ operations to it.In a single operation, you must replace every digit $$$d$$$ of the number with the decimal representation of integer $$$d + 1$$$. For example, $$$1912$$$ becomes $$$21023$$$ after applying the operation once.You have to find the length of $$$n$$$ after applying $$$m$$$ operations. Since the answer can be very large, print it modulo $$$10^9+7$$$.",[]844"Все готовятся к VK Fest 2021! Для того, чтобы зрителям была лучше видна главная сцена, планируется построить амфитеатр. В этой задаче мы будем рассматривать его сбоку — схематично он будет иметь форму лестницы из $$$n$$$ одинаковых квадратов. Лестница — это одна или более башен квадратов, выстроенных в ряд, где высоты башен невозрастают слева направо.На следующем рисунке можно видеть три разные фигуры из $$$12$$$ квадратов. Первые две фигуры — лестницы, а третья — нет.  Из эстетических соображений было решено, что амфитеатр должен быть симметричным. Формально, амфитеатр называется симметричным, если при отражении его схемы относительно прямой $$$x = y$$$ получается тот же самый рисунок (где ось $$$x$$$ направлена слева направо, а ось $$$y$$$ — снизу вверх). Например, первая лестница на рисунке выше — симметричная, а вторая — нет.  Кроме того, амфитеатр должен быть максимально компактным — а именно, сторона минимального квадрата, внутрь которого можно его поместить, должна быть как можно меньше.По заданному числу $$$n$$$ нарисуйте схему амфитеатра из ровно $$$n$$$ квадратов, удовлетворяющую всем условиям.",[]845"Martha — as a professional problemsetter — proposed a problem for a world-class contest. This is the problem statement:Tomorrow is Nadia's birthday, and Bardia (her brother) is assigned to make the balloons ready!There are n balloons (initially empty) that are tied to a straight line on certain positions x1, x2, ..., xn. Bardia inflates the balloons from left to right. As a result, i-th balloon gets bigger and bigger until its radius reaches the pressure endurance pi or it touches another previously-inflated balloon.  While Bardia was busy with the balloons, he wondered ""What will be the sum of radius of balloons after all of the balloons are inflated?"". Being a nerdy type of guy, he is now thinking about the problem instead of preparing his sister's birthday. Calculate the answer to Bardia's problem so that Nadia's birthday won't be balloon-less.Artha — Martha's student — claimed his solution got accepted. Martha (being his teacher for a long time!) knew he couldn't have solved the problem for real and thus thinks there is something wrong with the testcases. Artha isn't anyhow logical, which means there is no way for Martha to explain the wrong point in his algorithm. So, the only way is to find a testcase to prove him wrong!Artha's pseudo-code is shown below:  You should output a small testcase for the problem such that Artha's algorithm is incorrect. The algorithm's output is considered correct if it differs from the correct value by no more than 1.",[]846"Polycarp has guessed three positive integers $$$a$$$, $$$b$$$ and $$$c$$$. He keeps these numbers in secret, but he writes down four numbers on a board in arbitrary order — their pairwise sums (three numbers) and sum of all three numbers (one number). So, there are four numbers on a board in random order: $$$a+b$$$, $$$a+c$$$, $$$b+c$$$ and $$$a+b+c$$$.You have to guess three numbers $$$a$$$, $$$b$$$ and $$$c$$$ using given numbers. Print three guessed integers in any order.Pay attention that some given numbers $$$a$$$, $$$b$$$ and $$$c$$$ can be equal (it is also possible that $$$a=b=c$$$).",['math']847"Your working week consists of $$$n$$$ days numbered from $$$1$$$ to $$$n$$$, after day $$$n$$$ goes day $$$1$$$ again. And $$$3$$$ of them are days off. One of the days off is the last day, day $$$n$$$. You have to decide when the other two are.Choosing days off, you pursue two goals:   No two days should go one after the other. Note that you can't make day $$$1$$$ a day off because it follows day $$$n$$$.  Working segments framed by days off should be as dissimilar as possible in duration. More specifically, if the segments are of size $$$l_1$$$, $$$l_2$$$, and $$$l_3$$$ days long, you want to maximize $$$\min(|l_1 - l_2|, |l_2 - l_3|, |l_3 - l_1|)$$$. Output the maximum value of $$$\min(|l_1 - l_2|, |l_2 - l_3|, |l_3 - l_1|)$$$ that can be obtained.",['math']848"One fine October day a mathematics teacher Vasily Petrov went to a class and saw there n pupils who sat at the  desks, two people at each desk. Vasily quickly realized that number n is even. Like all true mathematicians, Vasily has all students numbered from 1 to n.But Vasily Petrov did not like the way the children were seated at the desks. According to him, the students whose numbers differ by 1, can not sit together, as they talk to each other all the time, distract others and misbehave.On the other hand, if a righthanded student sits at the left end of the desk and a lefthanded student sits at the right end of the desk, they hit elbows all the time and distract each other. In other cases, the students who sit at the same desk, do not interfere with each other.Vasily knows very well which students are lefthanders and which ones are righthanders, and he asks you to come up with any order that meets these two uncomplicated conditions (students do not talk to each other and do not bump their elbows). It is guaranteed that the input is such that at least one way to seat the students always exists.",[]849"Sonya decided that having her own hotel business is the best way of earning money because she can profit and rest wherever she wants.The country where Sonya lives is an endless line. There is a city in each integer coordinate on this line. She has $$$n$$$ hotels, where the $$$i$$$-th hotel is located in the city with coordinate $$$x_i$$$. Sonya is a smart girl, so she does not open two or more hotels in the same city.Sonya understands that her business needs to be expanded by opening new hotels, so she decides to build one more. She wants to make the minimum distance from this hotel to all others to be equal to $$$d$$$. The girl understands that there are many possible locations to construct such a hotel. Thus she wants to know the number of possible coordinates of the cities where she can build a new hotel. Because Sonya is lounging in a jacuzzi in one of her hotels, she is asking you to find the number of cities where she can build a new hotel so that the minimum distance from the original $$$n$$$ hotels to the new one is equal to $$$d$$$.",[]850"This is yet another problem dealing with regular bracket sequences.We should remind you that a bracket sequence is called regular, if by inserting «+» and «1» into it we can get a correct mathematical expression. For example, sequences «(())()», «()» and «(()(()))» are regular, while «)(», «(()» and «(()))(» are not. You are given a string of «(» and «)» characters. You are to find its longest substring that is a regular bracket sequence. You are to find the number of such substrings as well.",['strings']851"Monocarp and Bicarp live in Berland, where every bus ticket consists of $$$n$$$ digits ($$$n$$$ is an even number). During the evening walk Monocarp and Bicarp found a ticket where some of the digits have been erased. The number of digits that have been erased is even.Monocarp and Bicarp have decided to play a game with this ticket. Monocarp hates happy tickets, while Bicarp collects them. A ticket is considered happy if the sum of the first $$$\frac{n}{2}$$$ digits of this ticket is equal to the sum of the last $$$\frac{n}{2}$$$ digits.Monocarp and Bicarp take turns (and Monocarp performs the first of them). During each turn, the current player must replace any erased digit with any digit from $$$0$$$ to $$$9$$$. The game ends when there are no erased digits in the ticket.If the ticket is happy after all erased digits are replaced with decimal digits, then Bicarp wins. Otherwise, Monocarp wins. You have to determine who will win if both players play optimally.","['math', 'games']"852"The first algorithm for detecting a face on the image working in realtime was developed by Paul Viola and Michael Jones in 2001. A part of the algorithm is a procedure that computes Haar features. As part of this task, we consider a simplified model of this concept.Let's consider a rectangular image that is represented with a table of size n × m. The table elements are integers that specify the brightness of each pixel in the image.A feature also is a rectangular table of size n × m. Each cell of a feature is painted black or white.To calculate the value of the given feature at the given image, you must perform the following steps. First the table of the feature is put over the table of the image (without rotations or reflections), thus each pixel is entirely covered with either black or white cell. The value of a feature in the image is the value of W - B, where W is the total brightness of the pixels in the image, covered with white feature cells, and B is the total brightness of the pixels covered with black feature cells.Some examples of the most popular Haar features are given below.   Your task is to determine the number of operations that are required to calculate the feature by using the so-called prefix rectangles.A prefix rectangle is any rectangle on the image, the upper left corner of which coincides with the upper left corner of the image.You have a variable value, whose value is initially zero. In one operation you can count the sum of pixel values ​​at any prefix rectangle, multiply it by any integer and add to variable value.You are given a feature. It is necessary to calculate the minimum number of operations required to calculate the values of this attribute at an arbitrary image. For a better understanding of the statement, read the explanation of the first sample.",[]853"Two integer sequences existed initially, one of them was strictly increasing, and another one — strictly decreasing.Strictly increasing sequence is a sequence of integers $$$[x_1 < x_2 < \dots < x_k]$$$. And strictly decreasing sequence is a sequence of integers $$$[y_1 > y_2 > \dots > y_l]$$$. Note that the empty sequence and the sequence consisting of one element can be considered as increasing or decreasing.Elements of increasing sequence were inserted between elements of the decreasing one (and, possibly, before its first element and after its last element) without changing the order. For example, sequences $$$[1, 3, 4]$$$ and $$$[10, 4, 2]$$$ can produce the following resulting sequences: $$$[10, \textbf{1}, \textbf{3}, 4, 2, \textbf{4}]$$$, $$$[\textbf{1}, \textbf{3}, \textbf{4}, 10, 4, 2]$$$. The following sequence cannot be the result of these insertions: $$$[\textbf{1}, 10, \textbf{4}, 4, \textbf{3}, 2]$$$ because the order of elements in the increasing sequence was changed.Let the obtained sequence be $$$a$$$. This sequence $$$a$$$ is given in the input. Your task is to find any two suitable initial sequences. One of them should be strictly increasing, and another one — strictly decreasing. Note that the empty sequence and the sequence consisting of one element can be considered as increasing or decreasing.If there is a contradiction in the input and it is impossible to split the given sequence $$$a$$$ into one increasing sequence and one decreasing sequence, print ""NO"".",[]854"Gildong was hiking a mountain, walking by millions of trees. Inspired by them, he suddenly came up with an interesting idea for trees in data structures: What if we add another edge in a tree?Then he found that such tree-like graphs are called 1-trees. Since Gildong was bored of solving too many tree problems, he wanted to see if similar techniques in trees can be used in 1-trees as well. Instead of solving it by himself, he's going to test you by providing queries on 1-trees.First, he'll provide you a tree (not 1-tree) with $$$n$$$ vertices, then he will ask you $$$q$$$ queries. Each query contains $$$5$$$ integers: $$$x$$$, $$$y$$$, $$$a$$$, $$$b$$$, and $$$k$$$. This means you're asked to determine if there exists a path from vertex $$$a$$$ to $$$b$$$ that contains exactly $$$k$$$ edges after adding a bidirectional edge between vertices $$$x$$$ and $$$y$$$. A path can contain the same vertices and same edges multiple times. All queries are independent of each other; i.e. the added edge in a query is removed in the next query.",['trees']855"Once Bob decided to lay a parquet floor in his living room. The living room is of size n × m metres. Bob had planks of three types: a planks 1 × 2 meters, b planks 2 × 1 meters, and c planks 2 × 2 meters. Help Bob find out, if it is possible to parquet the living room with such a set of planks, and if it is possible, find one of the possible ways to do so. Bob doesn't have to use all the planks.",[]856"Vladik and Chloe decided to determine who of them is better at math. Vladik claimed that for any positive integer n he can represent fraction  as a sum of three distinct positive fractions in form .Help Vladik with that, i.e for a given n find three distinct positive integers x, y and z such that . Because Chloe can't check Vladik's answer if the numbers are large, he asks you to print numbers not exceeding 109.If there is no such answer, print -1.","['math', 'number theory']"857"There are $$$n$$$ students in the first grade of Nlogonia high school. The principal wishes to split the students into two classrooms (each student must be in exactly one of the classrooms). Two distinct students whose name starts with the same letter will be chatty if they are put in the same classroom (because they must have a lot in common). Let $$$x$$$ be the number of such pairs of students in a split. Pairs $$$(a, b)$$$ and $$$(b, a)$$$ are the same and counted only once.For example, if there are $$$6$$$ students: ""olivia"", ""jacob"", ""tanya"", ""jack"", ""oliver"" and ""jessica"", then:  splitting into two classrooms (""jack"", ""jacob"", ""jessica"", ""tanya"") and (""olivia"", ""oliver"") will give $$$x=4$$$ ($$$3$$$ chatting pairs in the first classroom, $$$1$$$ chatting pair in the second classroom),  splitting into two classrooms (""jack"", ""tanya"", ""olivia"") and (""jessica"", ""oliver"", ""jacob"") will give $$$x=1$$$ ($$$0$$$ chatting pairs in the first classroom, $$$1$$$ chatting pair in the second classroom). You are given the list of the $$$n$$$ names. What is the minimum $$$x$$$ we can obtain by splitting the students into classrooms?Note that it is valid to place all of the students in one of the classrooms, leaving the other one empty.",[]858"There is a given sequence of integers a1, a2, ..., an, where every number is from 1 to 3 inclusively. You have to replace the minimum number of numbers in it so that all the numbers in the sequence are equal to each other.",[]859"The Little Elephant loves permutations of integers from 1 to n very much. But most of all he loves sorting them. To sort a permutation, the Little Elephant repeatedly swaps some elements. As a result, he must receive a permutation 1, 2, 3, ..., n.This time the Little Elephant has permutation p1, p2, ..., pn. Its sorting program needs to make exactly m moves, during the i-th move it swaps elements that are at that moment located at the ai-th and the bi-th positions. But the Little Elephant's sorting program happened to break down and now on every step it can equiprobably either do nothing or swap the required elements.Now the Little Elephant doesn't even hope that the program will sort the permutation, but he still wonders: if he runs the program and gets some permutation, how much will the result of sorting resemble the sorted one? For that help the Little Elephant find the mathematical expectation of the number of permutation inversions after all moves of the program are completed.We'll call a pair of integers i, j (1 ≤ i < j ≤ n) an inversion in permutatuon p1, p2, ..., pn, if the following inequality holds: pi > pj.","['math', 'probabilities']"860"Mrs. Smith is trying to contact her husband, John Smith, but she forgot the secret phone number!The only thing Mrs. Smith remembered was that any permutation of $$$n$$$ can be a secret phone number. Only those permutations that minimize secret value might be the phone of her husband.The sequence of $$$n$$$ integers is called a permutation if it contains all integers from $$$1$$$ to $$$n$$$ exactly once.The secret value of a phone number is defined as the sum of the length of the longest increasing subsequence (LIS) and length of the longest decreasing subsequence (LDS). A subsequence $$$a_{i_1}, a_{i_2}, \ldots, a_{i_k}$$$ where $$$1\leq i_1 < i_2 < \ldots < i_k\leq n$$$ is called increasing if $$$a_{i_1} < a_{i_2} < a_{i_3} < \ldots < a_{i_k}$$$. If $$$a_{i_1} > a_{i_2} > a_{i_3} > \ldots > a_{i_k}$$$, a subsequence is called decreasing. An increasing/decreasing subsequence is called longest if it has maximum length among all increasing/decreasing subsequences.For example, if there is a permutation $$$[6, 4, 1, 7, 2, 3, 5]$$$, LIS of this permutation will be $$$[1, 2, 3, 5]$$$, so the length of LIS is equal to $$$4$$$. LDS can be $$$[6, 4, 1]$$$, $$$[6, 4, 2]$$$, or $$$[6, 4, 3]$$$, so the length of LDS is $$$3$$$.Note, the lengths of LIS and LDS can be different.So please help Mrs. Smith to find a permutation that gives a minimum sum of lengths of LIS and LDS.",[]861"The only difference between easy and hard versions is constraints.You are given a sequence $$$a$$$ consisting of $$$n$$$ positive integers.Let's define a three blocks palindrome as the sequence, consisting of at most two distinct elements (let these elements are $$$a$$$ and $$$b$$$, $$$a$$$ can be equal $$$b$$$) and is as follows: $$$[\underbrace{a, a, \dots, a}_{x}, \underbrace{b, b, \dots, b}_{y}, \underbrace{a, a, \dots, a}_{x}]$$$. There $$$x, y$$$ are integers greater than or equal to $$$0$$$. For example, sequences $$$[]$$$, $$$[2]$$$, $$$[1, 1]$$$, $$$[1, 2, 1]$$$, $$$[1, 2, 2, 1]$$$ and $$$[1, 1, 2, 1, 1]$$$ are three block palindromes but $$$[1, 2, 3, 2, 1]$$$, $$$[1, 2, 1, 2, 1]$$$ and $$$[1, 2]$$$ are not.Your task is to choose the maximum by length subsequence of $$$a$$$ that is a three blocks palindrome.You have to answer $$$t$$$ independent test cases.Recall that the sequence $$$t$$$ is a a subsequence of the sequence $$$s$$$ if $$$t$$$ can be derived from $$$s$$$ by removing zero or more elements without changing the order of the remaining elements. For example, if $$$s=[1, 2, 1, 3, 1, 2, 1]$$$, then possible subsequences are: $$$[1, 1, 1, 1]$$$, $$$[3]$$$ and $$$[1, 2, 1, 3, 1, 2, 1]$$$, but not $$$[3, 2, 3]$$$ and $$$[1, 1, 1, 1, 2]$$$.",[]862"Do you know a story about the three musketeers? Anyway, you will learn about its origins now.Richelimakieu is a cardinal in the city of Bearis. He is tired of dealing with crime by himself. He needs three brave warriors to help him to fight against bad guys.There are n warriors. Richelimakieu wants to choose three of them to become musketeers but it's not that easy. The most important condition is that musketeers must know each other to cooperate efficiently. And they shouldn't be too well known because they could be betrayed by old friends. For each musketeer his recognition is the number of warriors he knows, excluding other two musketeers.Help Richelimakieu! Find if it is possible to choose three musketeers knowing each other, and what is minimum possible sum of their recognitions.",['graphs']863"A famous gang of pirates, Sea Dogs, has come back to their hideout from one of their extravagant plunders. They want to split their treasure fairly amongst themselves, that is why You, their trusted financial advisor, devised a game to help them:All of them take a sit at their round table, some of them with the golden coins they have just stolen. At each iteration of the game if one of them has equal or more than 2 coins, he is eligible to the splitting and he gives one coin to each pirate sitting next to him. If there are more candidates (pirates with equal or more than 2 coins) then You are the one that chooses which one of them will do the splitting in that iteration. The game ends when there are no more candidates eligible to do the splitting. Pirates can call it a day, only when the game ends. Since they are beings with a finite amount of time at their disposal, they would prefer if the game that they are playing can end after finite iterations, and if so, they call it a good game. On the other hand, if no matter how You do the splitting, the game cannot end in finite iterations, they call it a bad game. Can You help them figure out before they start playing if the game will be good or bad?",['math']864"Let's denote correct match equation (we will denote it as CME) an equation $$$a + b = c$$$ there all integers $$$a$$$, $$$b$$$ and $$$c$$$ are greater than zero.For example, equations $$$2 + 2 = 4$$$ (||+||=||||) and $$$1 + 2 = 3$$$ (|+||=|||) are CME but equations $$$1 + 2 = 4$$$ (|+||=||||), $$$2 + 2 = 3$$$ (||+||=|||), and $$$0 + 1 = 1$$$ (+|=|) are not.Now, you have $$$n$$$ matches. You want to assemble a CME using all your matches. Unfortunately, it is possible that you can't assemble the CME using all matches. But you can buy some extra matches and then assemble CME!For example, if $$$n = 2$$$, you can buy two matches and assemble |+|=||, and if $$$n = 5$$$ you can buy one match and assemble ||+|=|||.   Calculate the minimum number of matches which you have to buy for assembling CME.Note, that you have to answer $$$q$$$ independent queries.",['math']865"Профиль горного хребта схематично задан в виде прямоугольной таблицы из символов «.» (пустое пространство) и «*» (часть горы). Каждый столбец таблицы содержит хотя бы одну «звёздочку». Гарантируется, что любой из символов «*» либо находится в нижней строке матрицы, либо непосредственно под ним находится другой символ «*».  ....................*..*.......*.**.......*.**..*...**.***********   Пример изображения горного хребта.  Маршрут туриста проходит через весь горный хребет слева направо. Каждый день турист перемещается вправо — в соседний столбец в схематичном изображении. Конечно, каждый раз он поднимается (или опускается) в самую верхнюю точку горы, которая находится в соответствующем столбце.Считая, что изначально турист находится в самой верхней точке в первом столбце, а закончит свой маршрут в самой верхней точке в последнем столбце, найдите две величины:  наибольший подъём за день (равен 0, если в профиле горного хребта нет ни одного подъёма),  наибольший спуск за день (равен 0, если в профиле горного хребта нет ни одного спуска). ",[]866"Yaroslav likes algorithms. We'll describe one of his favorite algorithms.  The algorithm receives a string as the input. We denote this input string as a.  The algorithm consists of some number of command. Сommand number i looks either as si >> wi, or as si <> wi, where si and wi are some possibly empty strings of length at most 7, consisting of digits and characters ""?"".  At each iteration, the algorithm looks for a command with the minimum index i, such that si occurs in a as a substring. If this command is not found the algorithm terminates.  Let's denote the number of the found command as k. In string a the first occurrence of the string sk is replaced by string wk. If the found command at that had form sk >> wk, then the algorithm continues its execution and proceeds to the next iteration. Otherwise, the algorithm terminates.  The value of string a after algorithm termination is considered to be the output of the algorithm. Yaroslav has a set of n positive integers, he needs to come up with his favorite algorithm that will increase each of the given numbers by one. More formally, if we consider each number as a string representing the decimal representation of the number, then being run on each of these strings separately, the algorithm should receive the output string that is a recording of the corresponding number increased by one.Help Yaroslav.",[]867"Hongcow is ruler of the world. As ruler of the world, he wants to make it easier for people to travel by road within their own countries.The world can be modeled as an undirected graph with n nodes and m edges. k of the nodes are home to the governments of the k countries that make up the world.There is at most one edge connecting any two nodes and no edge connects a node to itself. Furthermore, for any two nodes corresponding to governments, there is no path between those two nodes. Any graph that satisfies all of these conditions is stable.Hongcow wants to add as many edges as possible to the graph while keeping it stable. Determine the maximum number of edges Hongcow can add.",['graphs']868"Yet another round on DecoForces is coming! Grandpa Maks wanted to participate in it but someone has stolen his precious sofa! And how can one perform well with such a major loss?Fortunately, the thief had left a note for Grandpa Maks. This note got Maks to the sofa storehouse. Still he had no idea which sofa belongs to him as they all looked the same!The storehouse is represented as matrix n × m. Every sofa takes two neighbouring by some side cells. No cell is covered by more than one sofa. There can be empty cells.Sofa A is standing to the left of sofa B if there exist two such cells a and b that xa < xb, a is covered by A and b is covered by B. Sofa A is standing to the top of sofa B if there exist two such cells a and b that ya < yb, a is covered by A and b is covered by B. Right and bottom conditions are declared the same way. Note that in all conditions A ≠ B. Also some sofa A can be both to the top of another sofa B and to the bottom of it. The same is for left and right conditions.The note also stated that there are cntl sofas to the left of Grandpa Maks's sofa, cntr — to the right, cntt — to the top and cntb — to the bottom.Grandpa Maks asks you to help him to identify his sofa. It is guaranteed that there is no more than one sofa of given conditions.Output the number of Grandpa Maks's sofa. If there is no such sofa that all the conditions are met for it then output -1.",[]869"There is a house with $$$n$$$ flats situated on the main street of Berlatov. Vova is watching this house every night. The house can be represented as an array of $$$n$$$ integer numbers $$$a_1, a_2, \dots, a_n$$$, where $$$a_i = 1$$$ if in the $$$i$$$-th flat the light is on and $$$a_i = 0$$$ otherwise.Vova thinks that people in the $$$i$$$-th flats are disturbed and cannot sleep if and only if $$$1 < i < n$$$ and $$$a_{i - 1} = a_{i + 1} = 1$$$ and $$$a_i = 0$$$.Vova is concerned by the following question: what is the minimum number $$$k$$$ such that if people from exactly $$$k$$$ pairwise distinct flats will turn off the lights then nobody will be disturbed? Your task is to find this number $$$k$$$.",[]870"You are given an array $$$a$$$ of $$$n$$$ integers and an integer $$$s$$$. It is guaranteed that $$$n$$$ is odd.In one operation you can either increase or decrease any single element by one. Calculate the minimum number of operations required to make the median of the array being equal to $$$s$$$.The median of the array with odd length is the value of the element which is located on the middle position after the array is sorted. For example, the median of the array $$$6, 5, 8$$$ is equal to $$$6$$$, since if we sort this array we will get $$$5, 6, 8$$$, and $$$6$$$ is located on the middle position.",[]871"Today, like every year at SWERC, the $$$n^2$$$ contestants have gathered outside the venue to take a drone photo. Jennifer, the social media manager for the event, has arranged them into an $$$n\times n$$$ square. Being very good at her job, she knows that the contestant standing on the intersection of the $$$i$$$-th row with the $$$j$$$-th column is $$$a_{i,j}$$$ years old. Coincidentally, she notices that no two contestants have the same age, and that everyone is between $$$1$$$ and $$$n^2$$$ years old.Jennifer is planning to have some contestants hold a banner with the ICPC logo parallel to the ground, so that it is clearly visible in the aerial picture. Here are the steps that she is going to follow in order to take the perfect SWERC drone photo.  First of all, Jennifer is going to select four contestants standing on the vertices of an axis-aligned rectangle.  Then, she will have the two younger contestants hold one of the poles, while the two older contestants will hold the other pole.  Finally, she will unfold the banner, using the poles to support its two ends. Obviously, this can only be done if the two poles are parallel and do not cross, as shown in the pictures below.    Being very indecisive, Jennifer would like to try out all possible arrangements for the banner, but she is worried that this may cause the contestants to be late for the competition. How many different ways are there to choose the four contestants holding the poles in order to take a perfect photo? Two choices are considered different if at least one contestant is included in one but not the other.",['math']872"Sagheer is working at a kindergarten. There are n children and m different toys. These children use well-defined protocols for playing with the toys:  Each child has a lovely set of toys that he loves to play with. He requests the toys one after another at distinct moments of time. A child starts playing if and only if he is granted all the toys in his lovely set. If a child starts playing, then sooner or later he gives the toys back. No child keeps the toys forever. Children request toys at distinct moments of time. No two children request a toy at the same time. If a child is granted a toy, he never gives it back until he finishes playing with his lovely set. If a child is not granted a toy, he waits until he is granted this toy. He can't request another toy while waiting. If two children are waiting for the same toy, then the child who requested it first will take the toy first.Children don't like to play with each other. That's why they never share toys. When a child requests a toy, then granting the toy to this child depends on whether the toy is free or not. If the toy is free, Sagheer will give it to the child. Otherwise, the child has to wait for it and can't request another toy.Children are smart and can detect if they have to wait forever before they get the toys they want. In such case they start crying. In other words, a crying set is a set of children in which each child is waiting for a toy that is kept by another child in the set.Now, we have reached a scenario where all the children made all the requests for their lovely sets, except for one child x that still has one last request for his lovely set. Some children are playing while others are waiting for a toy, but no child is crying, and no one has yet finished playing. If the child x is currently waiting for some toy, he makes his last request just after getting that toy. Otherwise, he makes the request right away. When child x will make his last request, how many children will start crying?You will be given the scenario and q independent queries. Each query will be of the form x y meaning that the last request of the child x is for the toy y. Your task is to help Sagheer find the size of the maximal crying set when child x makes his last request.","['graphs', 'trees']"873"CQXYM found a rectangle $$$A$$$ of size $$$n \times m$$$. There are $$$n$$$ rows and $$$m$$$ columns of blocks. Each block of the rectangle is an obsidian block or empty. CQXYM can change an obsidian block to an empty block or an empty block to an obsidian block in one operation.A rectangle $$$M$$$ size of $$$a \times b$$$ is called a portal if and only if it satisfies the following conditions:  $$$a \geq 5,b \geq 4$$$.  For all $$$1 < x < a$$$, blocks $$$M_{x,1}$$$ and $$$M_{x,b}$$$ are obsidian blocks.  For all $$$1 < x < b$$$, blocks $$$M_{1,x}$$$ and $$$M_{a,x}$$$ are obsidian blocks.  For all $$$1<x<a,1<y<b$$$, block $$$M_{x,y}$$$ is an empty block.  $$$M_{1, 1}, M_{1, b}, M_{a, 1}, M_{a, b}$$$ can be any type.  Note that the there must be $$$a$$$ rows and $$$b$$$ columns, not $$$b$$$ rows and $$$a$$$ columns.Note that corners can be any typeCQXYM wants to know the minimum number of operations he needs to make at least one sub-rectangle a portal.",[]874"Shubham has an array $$$a$$$ of size $$$n$$$, and wants to select exactly $$$x$$$ elements from it, such that their sum is odd. These elements do not have to be consecutive. The elements of the array are not guaranteed to be distinct.Tell him whether he can do so.",['math']875"You are given an array $$$a$$$ of length $$$n$$$ consisting of integers. You can apply the following operation, consisting of several steps, on the array $$$a$$$ zero or more times:   you select two different numbers in the array $$$a_i$$$ and $$$a_j$$$;  you remove $$$i$$$-th and $$$j$$$-th elements from the array. For example, if $$$n=6$$$ and $$$a=[1, 6, 1, 1, 4, 4]$$$, then you can perform the following sequence of operations:   select $$$i=1, j=5$$$. The array $$$a$$$ becomes equal to $$$[6, 1, 1, 4]$$$;  select $$$i=1, j=2$$$. The array $$$a$$$ becomes equal to $$$[1, 4]$$$. What can be the minimum size of the array after applying some sequence of operations to it?",[]876"Bessie has way too many friends because she is everyone's favorite cow! Her new friend Rabbit is trying to hop over so they can play! More specifically, he wants to get from $$$(0,0)$$$ to $$$(x,0)$$$ by making multiple hops. He is only willing to hop from one point to another point on the 2D plane if the Euclidean distance between the endpoints of a hop is one of its $$$n$$$ favorite numbers: $$$a_1, a_2, \ldots, a_n$$$. What is the minimum number of hops Rabbit needs to get from $$$(0,0)$$$ to $$$(x,0)$$$? Rabbit may land on points with non-integer coordinates. It can be proved that Rabbit can always reach his destination.Recall that the Euclidean distance between points $$$(x_i, y_i)$$$ and $$$(x_j, y_j)$$$ is $$$\sqrt{(x_i-x_j)^2+(y_i-y_j)^2}$$$.For example, if Rabbit has favorite numbers $$$1$$$ and $$$3$$$ he could hop from $$$(0,0)$$$ to $$$(4,0)$$$ in two hops as shown below. Note that there also exists other valid ways to hop to $$$(4,0)$$$ in $$$2$$$ hops (e.g. $$$(0,0)$$$ $$$\rightarrow$$$ $$$(2,-\sqrt{5})$$$ $$$\rightarrow$$$ $$$(4,0)$$$).    Here is a graphic for the first example. Both hops have distance $$$3$$$, one of Rabbit's favorite numbers. In other words, each time Rabbit chooses some number $$$a_i$$$ and hops with distance equal to $$$a_i$$$ in any direction he wants. The same number can be used multiple times.","['math', 'geometry']"877"After many unsuccessful tries, Mashtali decided to copy modify an AtCoder problem. So here is his copied new problem:There is a tree with $$$n$$$ vertices and some non-empty set of the vertices are pinned to the ground.Two players play a game against each other on the tree. They alternately perform the following action:  Remove an edge from the tree, then remove every connected component that has no pinned vertex.The player who cannot move loses(every edge has been deleted already). You are given the tree, but not the set of the pinned vertices. Your task is to determine, for each $$$k$$$, the winner of the game, if only the vertices $$$1, 2, 3, \ldots, k$$$ are pinned and both players play optimally.","['trees', 'games']"878"This is the easy version of the problem. The difference between the versions is the constraints on $$$a_i$$$. You can make hacks only if all versions of the problem are solved.Little Dormi has recently received a puzzle from his friend and needs your help to solve it. The puzzle consists of an upright board with $$$n$$$ rows and $$$m$$$ columns of cells, some empty and some filled with blocks of sand, and $$$m$$$ non-negative integers $$$a_1,a_2,\ldots,a_m$$$ ($$$0 \leq a_i \leq n$$$). In this version of the problem, $$$a_i$$$ will be equal to the number of blocks of sand in column $$$i$$$.When a cell filled with a block of sand is disturbed, the block of sand will fall from its cell to the sand counter at the bottom of the column (each column has a sand counter). While a block of sand is falling, other blocks of sand that are adjacent at any point to the falling block of sand will also be disturbed and start to fall. Specifically, a block of sand disturbed at a cell $$$(i,j)$$$ will pass through all cells below and including the cell $$$(i,j)$$$ within the column, disturbing all adjacent cells along the way. Here, the cells adjacent to a cell $$$(i,j)$$$ are defined as $$$(i-1,j)$$$, $$$(i,j-1)$$$, $$$(i+1,j)$$$, and $$$(i,j+1)$$$ (if they are within the grid). Note that the newly falling blocks can disturb other blocks.In one operation you are able to disturb any piece of sand. The puzzle is solved when there are at least $$$a_i$$$ blocks of sand counted in the $$$i$$$-th sand counter for each column from $$$1$$$ to $$$m$$$.You are now tasked with finding the minimum amount of operations in order to solve the puzzle. Note that Little Dormi will never give you a puzzle that is impossible to solve.",['graphs']879"Professor Vasechkin is studying evolution of worms. Recently he put forward hypotheses that all worms evolve by division. There are n forms of worms. Worms of these forms have lengths a1, a2, ..., an. To prove his theory, professor needs to find 3 different forms that the length of the first form is equal to sum of lengths of the other two forms. Help him to do this.",[]880"The girl named Masha was walking in the forest and found a complete binary tree of height $$$n$$$ and a permutation $$$p$$$ of length $$$m=2^n$$$.A complete binary tree of height $$$n$$$ is a rooted tree such that every vertex except the leaves has exactly two sons, and the length of the path from the root to any of the leaves is $$$n$$$. The picture below shows the complete binary tree for $$$n=2$$$.A permutation is an array consisting of $$$n$$$ different integers from $$$1$$$ to $$$n$$$. For example, [$$$2,3,1,5,4$$$] is a permutation, but [$$$1,2,2$$$] is not ($$$2$$$ occurs twice), and [$$$1,3,4$$$] is also not a permutation ($$$n=3$$$, but there is $$$4$$$ in the array).Let's enumerate $$$m$$$ leaves of this tree from left to right. The leaf with the number $$$i$$$ contains the value $$$p_i$$$ ($$$1 \le i \le m$$$).For example, if $$$n = 2$$$, $$$p = [3, 1, 4, 2]$$$, the tree will look like this:  Masha considers a tree beautiful if the values in its leaves are ordered from left to right in increasing order.In one operation, Masha can choose any non-leaf vertex of the tree and swap its left and right sons (along with their subtrees).For example, if Masha applies this operation to the root of the tree discussed above, it will take the following form:  Help Masha understand if she can make a tree beautiful in a certain number of operations. If she can, then output the minimum number of operations to make the tree beautiful.","['graphs', 'trees']"881"Andrewid the Android is a galaxy-famous detective. He is now investigating the case of vandalism at the exhibition of contemporary art.The main exhibit is a construction of n matryoshka dolls that can be nested one into another. The matryoshka dolls are numbered from 1 to n. A matryoshka with a smaller number can be nested in a matryoshka with a higher number, two matryoshkas can not be directly nested in the same doll, but there may be chain nestings, for example, 1 → 2 → 4 → 5. In one second, you can perform one of the two following operations:  Having a matryoshka a that isn't nested in any other matryoshka and a matryoshka b, such that b doesn't contain any other matryoshka and is not nested in any other matryoshka, you may put a in b;  Having a matryoshka a directly contained in matryoshka b, such that b is not nested in any other matryoshka, you may get a out of b. According to the modern aesthetic norms the matryoshka dolls on display were assembled in a specific configuration, i.e. as several separate chains of nested matryoshkas, but the criminal, following the mysterious plan, took out all the dolls and assembled them into a single large chain (1 → 2 → ... → n). In order to continue the investigation Andrewid needs to know in what minimum time it is possible to perform this action.",[]882"One day Vasya painted a Cartesian coordinate system on a piece of paper and marked some set of points (x1, y1), (x2, y2), ..., (xn, yn). Let's define neighbors for some fixed point from the given set (x, y):   point (x', y') is (x, y)'s right neighbor, if x' > x and y' = y  point (x', y') is (x, y)'s left neighbor, if x' < x and y' = y  point (x', y') is (x, y)'s lower neighbor, if x' = x and y' < y  point (x', y') is (x, y)'s upper neighbor, if x' = x and y' > y We'll consider point (x, y) from the given set supercentral, if it has at least one upper, at least one lower, at least one left and at least one right neighbor among this set's points.Vasya marked quite many points on the paper. Analyzing the picture manually is rather a challenge, so Vasya asked you to help him. Your task is to find the number of supercentral points in the given set.",[]883"Your favorite music streaming platform has formed a perfectly balanced playlist exclusively for you. The playlist consists of $$$n$$$ tracks numbered from $$$1$$$ to $$$n$$$. The playlist is automatic and cyclic: whenever track $$$i$$$ finishes playing, track $$$i+1$$$ starts playing automatically; after track $$$n$$$ goes track $$$1$$$.For each track $$$i$$$, you have estimated its coolness $$$a_i$$$. The higher $$$a_i$$$ is, the cooler track $$$i$$$ is.Every morning, you choose a track. The playlist then starts playing from this track in its usual cyclic fashion. At any moment, you remember the maximum coolness $$$x$$$ of already played tracks. Once you hear that a track with coolness strictly less than $$$\frac{x}{2}$$$ (no rounding) starts playing, you turn off the music immediately to keep yourself in a good mood.For each track $$$i$$$, find out how many tracks you will listen to before turning off the music if you start your morning with track $$$i$$$, or determine that you will never turn the music off. Note that if you listen to the same track several times, every time must be counted.",[]884"One day Dima and Alex had an argument about the price and quality of laptops. Dima thinks that the more expensive a laptop is, the better it is. Alex disagrees. Alex thinks that there are two laptops, such that the price of the first laptop is less (strictly smaller) than the price of the second laptop but the quality of the first laptop is higher (strictly greater) than the quality of the second laptop.Please, check the guess of Alex. You are given descriptions of n laptops. Determine whether two described above laptops exist.",[]885"After getting bored by playing with crayons, you decided to switch to Legos! Today, you're working with a long strip, with height $$$1$$$ and length $$$n$$$, some positions of which are occupied by $$$1$$$ by $$$1$$$ Lego pieces.In one second, you can either remove two adjacent Lego pieces from the strip (if both are present), or add two Lego pieces to adjacent positions (if both are absent). You can only add or remove Lego's at two adjacent positions at the same time, as otherwise your chubby fingers run into precision issues.You want to know exactly how much time you'll spend playing with Legos. You value efficiency, so given some starting state and some ending state, you'll always spend the least number of seconds to transform the starting state into the ending state. If it's impossible to transform the starting state into the ending state, you just skip it (so you spend $$$0$$$ seconds).The issue is that, for some positions, you don't remember whether there were Legos there or not (in either the starting state, the ending state, or both). Over all pairs of (starting state, ending state) that are consistent with your memory, find the total amount of time it will take to transform the starting state to the ending state. Print this value modulo $$$1\,000\,000\,007$$$ ($$$10^9 + 7$$$). ",['math']886"After too much playing on paper, Iahub has switched to computer games. The game he plays is called ""Block Towers"". It is played in a rectangular grid with n rows and m columns (it contains n × m cells). The goal of the game is to build your own city. Some cells in the grid are big holes, where Iahub can't build any building. The rest of cells are empty. In some empty cell Iahub can build exactly one tower of two following types:  Blue towers. Each has population limit equal to 100.  Red towers. Each has population limit equal to 200. However, it can be built in some cell only if in that moment at least one of the neighbouring cells has a Blue Tower. Two cells are neighbours is they share a side. Iahub is also allowed to destroy a building from any cell. He can do this operation as much as he wants. After destroying a building, the other buildings are not influenced, and the destroyed cell becomes empty (so Iahub can build a tower in this cell if needed, see the second example for such a case).Iahub can convince as many population as he wants to come into his city. So he needs to configure his city to allow maximum population possible. Therefore he should find a sequence of operations that builds the city in an optimal way, so that total population limit is as large as possible.He says he's the best at this game, but he doesn't have the optimal solution. Write a program that calculates the optimal one, to show him that he's not as good as he thinks. ",['graphs']887"You have a fence consisting of $$$n$$$ vertical boards. The width of each board is $$$1$$$. The height of the $$$i$$$-th board is $$$a_i$$$. You think that the fence is great if there is no pair of adjacent boards having the same height. More formally, the fence is great if and only if for all indices from $$$2$$$ to $$$n$$$, the condition $$$a_{i-1} \neq a_i$$$ holds.Unfortunately, it is possible that now your fence is not great. But you can change it! You can increase the length of the $$$i$$$-th board by $$$1$$$, but you have to pay $$$b_i$$$ rubles for it. The length of each board can be increased any number of times (possibly, zero).Calculate the minimum number of rubles you have to spend to make the fence great again!You have to answer $$$q$$$ independent queries.",[]888"For her birthday Alice received an interesting gift from her friends – The Light Square. The Light Square game is played on an $$$N \times N$$$ lightbulbs square board with a magical lightbulb bar of size $$$N \times 1$$$ that has magical properties. At the start of the game some lights on the square board and magical bar are turned on. The goal of the game is to transform the starting light square board pattern into some other pattern using the magical bar without rotating the square board. The magical bar works as follows: It can be placed on any row or column The orientation of the magical lightbulb must be left to right or top to bottom for it to keep its magical properties The entire bar needs to be fully placed on a board The lights of the magical bar never change If the light on the magical bar is the same as the light of the square it is placed on it will switch the light on the square board off, otherwise it will switch the light on The magical bar can be used an infinite number of times Alice has a hard time transforming her square board into the pattern Bob gave her. Can you help her transform the board or let her know it is impossible? If there are multiple solutions print any. ",[]889"Andryusha goes through a park each day. The squares and paths between them look boring to Andryusha, so he decided to decorate them.The park consists of n squares connected with (n - 1) bidirectional paths in such a way that any square is reachable from any other using these paths. Andryusha decided to hang a colored balloon at each of the squares. The baloons' colors are described by positive integers, starting from 1. In order to make the park varicolored, Andryusha wants to choose the colors in a special way. More precisely, he wants to use such colors that if a, b and c are distinct squares that a and b have a direct path between them, and b and c have a direct path between them, then balloon colors on these three squares are distinct.Andryusha wants to use as little different colors as possible. Help him to choose the colors!","['graphs', 'trees']"890"This is an interactive problem. Remember to flush your output while communicating with the testing program. You may use fflush(stdout) in C++, system.out.flush() in Java, stdout.flush() in Python or flush(output) in Pascal to flush the output. If you use some other programming language, consult its documentation. You may also refer to the guide on interactive problems: https://codeforces.com/blog/entry/45307.You are given a string $$$t$$$ consisting of $$$n$$$ lowercase Latin letters. This string was cyphered as follows: initially, the jury had a string $$$s$$$ consisting of $$$n$$$ lowercase Latin letters. Then they applied a sequence of no more than $$$n$$$ (possibly zero) operations. $$$i$$$-th operation is denoted by two integers $$$a_i$$$ and $$$b_i$$$ ($$$1 \le a_i, b_i \le n$$$), and means swapping two elements of the string with indices $$$a_i$$$ and $$$b_i$$$. All operations were done in the order they were placed in the sequence. For example, if $$$s$$$ is xyz and $$$2$$$ following operations are performed: $$$a_1 = 1, b_1 = 2$$$; $$$a_2 = 2, b_2 = 3$$$, then after the first operation the current string is yxz, and after the second operation the current string is yzx, so $$$t$$$ is yzx.You are asked to restore the original string $$$s$$$. Unfortunately, you have no information about the operations used in the algorithm (you don't even know if there were any operations in the sequence). But you may run the same sequence of operations on any string you want, provided that it contains only lowercase Latin letters and its length is $$$n$$$, and get the resulting string after those operations.Can you guess the original string $$$s$$$ asking the testing system to run the sequence of swaps no more than $$$3$$$ times?The string $$$s$$$ and the sequence of swaps are fixed in each test; the interactor doesn't try to adapt the test to your solution.",['math']891"In the year of $$$30XX$$$ participants of some world programming championship live in a single large hotel. The hotel has $$$n$$$ floors. Each floor has $$$m$$$ sections with a single corridor connecting all of them. The sections are enumerated from $$$1$$$ to $$$m$$$ along the corridor, and all sections with equal numbers on different floors are located exactly one above the other. Thus, the hotel can be represented as a rectangle of height $$$n$$$ and width $$$m$$$. We can denote sections with pairs of integers $$$(i, j)$$$, where $$$i$$$ is the floor, and $$$j$$$ is the section number on the floor.The guests can walk along the corridor on each floor, use stairs and elevators. Each stairs or elevator occupies all sections $$$(1, x)$$$, $$$(2, x)$$$, $$$\ldots$$$, $$$(n, x)$$$ for some $$$x$$$ between $$$1$$$ and $$$m$$$. All sections not occupied with stairs or elevators contain guest rooms. It takes one time unit to move between neighboring sections on the same floor or to move one floor up or down using stairs. It takes one time unit to move up to $$$v$$$ floors in any direction using an elevator. You can assume you don't have to wait for an elevator, and the time needed to enter or exit an elevator is negligible.You are to process $$$q$$$ queries. Each query is a question ""what is the minimum time needed to go from a room in section $$$(x_1, y_1)$$$ to a room in section $$$(x_2, y_2)$$$?""",[]892"Summer holidays! Someone is going on trips, someone is visiting grandparents, but someone is trying to get a part-time job. This summer Noora decided that she wants to earn some money, and took a job in a shop as an assistant.Shop, where Noora is working, has a plan on the following n days. For each day sales manager knows exactly, that in i-th day ki products will be put up for sale and exactly li clients will come to the shop that day. Also, the manager is sure, that everyone, who comes to the shop, buys exactly one product or, if there aren't any left, leaves the shop without buying anything. Moreover, due to the short shelf-life of the products, manager established the following rule: if some part of the products left on the shelves at the end of the day, that products aren't kept on the next day and are sent to the dump.For advertising purposes manager offered to start a sell-out in the shop. He asked Noora to choose any f days from n next for sell-outs. On each of f chosen days the number of products were put up for sale would be doubled. Thus, if on i-th day shop planned to put up for sale ki products and Noora has chosen this day for sell-out, shelves of the shop would keep 2·ki products. Consequently, there is an opportunity to sell two times more products on days of sell-out.Noora's task is to choose f days to maximize total number of sold products. She asks you to help her with such a difficult problem.",[]893"You are given a permutation $$$p$$$ of integers from $$$0$$$ to $$$n-1$$$ (each of them occurs exactly once). Initially, the permutation is not sorted (that is, $$$p_i>p_{i+1}$$$ for at least one $$$1 \le i \le n - 1$$$). The permutation is called $$$X$$$-sortable for some non-negative integer $$$X$$$ if it is possible to sort the permutation by performing the operation below some finite number of times:   Choose two indices $$$i$$$ and $$$j$$$ $$$(1 \le i \lt j \le n)$$$ such that $$$p_i \& p_j = X$$$.  Swap $$$p_i$$$ and $$$p_j$$$. Here $$$\&$$$ denotes the bitwise AND operation.Find the maximum value of $$$X$$$ such that $$$p$$$ is $$$X$$$-sortable. It can be shown that there always exists some value of $$$X$$$ such that $$$p$$$ is $$$X$$$-sortable.",[]894"A frog is currently at the point $$$0$$$ on a coordinate axis $$$Ox$$$. It jumps by the following algorithm: the first jump is $$$a$$$ units to the right, the second jump is $$$b$$$ units to the left, the third jump is $$$a$$$ units to the right, the fourth jump is $$$b$$$ units to the left, and so on.Formally:   if the frog has jumped an even number of times (before the current jump), it jumps from its current position $$$x$$$ to position $$$x+a$$$;  otherwise it jumps from its current position $$$x$$$ to position $$$x-b$$$. Your task is to calculate the position of the frog after $$$k$$$ jumps.But... One more thing. You are watching $$$t$$$ different frogs so you have to answer $$$t$$$ independent queries.",['math']895"A little boy Laurenty has been playing his favourite game Nota for quite a while and is now very hungry. The boy wants to make sausage and cheese sandwiches, but first, he needs to buy a sausage and some cheese.The town where Laurenty lives in is not large. The houses in it are located in two rows, n houses in each row. Laurenty lives in the very last house of the second row. The only shop in town is placed in the first house of the first row.The first and second rows are separated with the main avenue of the city. The adjacent houses of one row are separated by streets.Each crosswalk of a street or an avenue has some traffic lights. In order to cross the street, you need to press a button on the traffic light, wait for a while for the green light and cross the street. Different traffic lights can have different waiting time.The traffic light on the crosswalk from the j-th house of the i-th row to the (j + 1)-th house of the same row has waiting time equal to aij (1 ≤ i ≤ 2, 1 ≤ j ≤ n - 1). For the traffic light on the crossing from the j-th house of one row to the j-th house of another row the waiting time equals bj (1 ≤ j ≤ n). The city doesn't have any other crossings.The boy wants to get to the store, buy the products and go back. The main avenue of the city is wide enough, so the boy wants to cross it exactly once on the way to the store and exactly once on the way back home. The boy would get bored if he had to walk the same way again, so he wants the way home to be different from the way to the store in at least one crossing.    Figure to the first sample. Help Laurenty determine the minimum total time he needs to wait at the crossroads.",[]896"A class of students got bored wearing the same pair of shoes every day, so they decided to shuffle their shoes among themselves. In this problem, a pair of shoes is inseparable and is considered as a single object.There are $$$n$$$ students in the class, and you are given an array $$$s$$$ in non-decreasing order, where $$$s_i$$$ is the shoe size of the $$$i$$$-th student. A shuffling of shoes is valid only if no student gets their own shoes and if every student gets shoes of size greater than or equal to their size. You have to output a permutation $$$p$$$ of $$$\{1,2,\ldots,n\}$$$ denoting a valid shuffling of shoes, where the $$$i$$$-th student gets the shoes of the $$$p_i$$$-th student ($$$p_i \ne i$$$). And output $$$-1$$$ if a valid shuffling does not exist.A permutation is an array consisting of $$$n$$$ distinct integers from $$$1$$$ to $$$n$$$ in arbitrary order. For example, $$$[2,3,1,5,4]$$$ is a permutation, but $$$[1,2,2]$$$ is not a permutation ($$$2$$$ appears twice in the array) and $$$[1,3,4]$$$ is also not a permutation ($$$n=3$$$ but there is $$$4$$$ in the array).",[]897"Helen works in Metropolis airport. She is responsible for creating a departure schedule. There are n flights that must depart today, the i-th of them is planned to depart at the i-th minute of the day.Metropolis airport is the main transport hub of Metropolia, so it is difficult to keep the schedule intact. This is exactly the case today: because of technical issues, no flights were able to depart during the first k minutes of the day, so now the new departure schedule must be created.All n scheduled flights must now depart at different minutes between (k + 1)-th and (k + n)-th, inclusive. However, it's not mandatory for the flights to depart in the same order they were initially scheduled to do so — their order in the new schedule can be different. There is only one restriction: no flight is allowed to depart earlier than it was supposed to depart in the initial schedule.Helen knows that each minute of delay of the i-th flight costs airport ci burles. Help her find the order for flights to depart in the new schedule that minimizes the total cost for the airport.",[]898"Little penguin Polo adores strings. But most of all he adores strings of length n.One day he wanted to find a string that meets the following conditions:  The string consists of n lowercase English letters (that is, the string's length equals n), exactly k of these letters are distinct.  No two neighbouring letters of a string coincide; that is, if we represent a string as s = s1s2... sn, then the following inequality holds, si ≠ si + 1(1 ≤ i < n).  Among all strings that meet points 1 and 2, the required string is lexicographically smallest. Help him find such string or state that such string doesn't exist.String x = x1x2... xp is lexicographically less than string y = y1y2... yq, if either p < q and x1 = y1, x2 = y2, ... , xp = yp, or there is such number r (r < p, r < q), that x1 = y1, x2 = y2, ... , xr = yr and xr + 1 < yr + 1. The characters of the strings are compared by their ASCII codes.",[]899"Boy Dima gave Julian a birthday present — set $$$B$$$ consisting of positive integers. However, he didn't know, that Julian hates sets, but enjoys bipartite graphs more than anything else!Julian was almost upset, but her friend Alex said, that he can build an undirected graph using this set in such a way: let all integer numbers be vertices, then connect any two $$$i$$$ and $$$j$$$ with an edge if $$$|i - j|$$$ belongs to $$$B$$$.Unfortunately, Julian doesn't like the graph, that was built using $$$B$$$. Alex decided to rectify the situation, so he wants to erase some numbers from $$$B$$$, so that graph built using the new set is bipartite. The difficulty of this task is that the graph, Alex has to work with, has an infinite number of vertices and edges! It is impossible to solve this task alone, so Alex asks you for help. Write a program that erases a subset of minimum size from $$$B$$$ so that graph constructed on the new set is bipartite.Recall, that graph is bipartite if all its vertices can be divided into two disjoint sets such that every edge connects a vertex from different sets.","['math', 'number theory']"900"Everybody knows that opposites attract. That is the key principle of the ""Perfect Matching"" dating agency. The ""Perfect Matching"" matchmakers have classified each registered customer by his interests and assigned to the i-th client number ti ( - 10 ≤ ti ≤ 10). Of course, one number can be assigned to any number of customers.""Perfect Matching"" wants to advertise its services and publish the number of opposite couples, that is, the couples who have opposite values of t. Each couple consists of exactly two clients. The customer can be included in a couple an arbitrary number of times. Help the agency and write the program that will find the sought number by the given sequence t1, t2, ..., tn. For example, if t = (1,  - 1, 1,  - 1), then any two elements ti and tj form a couple if i and j have different parity. Consequently, in this case the sought number equals 4.Of course, a client can't form a couple with him/herself.",['math']901"Let's call a number a binary decimal if it's a positive integer and all digits in its decimal notation are either $$$0$$$ or $$$1$$$. For example, $$$1\,010\,111$$$ is a binary decimal, while $$$10\,201$$$ and $$$787\,788$$$ are not.Given a number $$$n$$$, you are asked to represent $$$n$$$ as a sum of some (not necessarily distinct) binary decimals. Compute the smallest number of binary decimals required for that.",['math']902"This problem is different from the easy version. In this version Ujan makes at most $$$2n$$$ swaps. In addition, $$$k \le 1000, n \le 50$$$ and it is necessary to print swaps themselves. You can hack this problem if you solve it. But you can hack the previous problem only if you solve both problems.After struggling and failing many times, Ujan decided to try to clean up his house again. He decided to get his strings in order first.Ujan has two distinct strings $$$s$$$ and $$$t$$$ of length $$$n$$$ consisting of only of lowercase English characters. He wants to make them equal. Since Ujan is lazy, he will perform the following operation at most $$$2n$$$ times: he takes two positions $$$i$$$ and $$$j$$$ ($$$1 \le i,j \le n$$$, the values $$$i$$$ and $$$j$$$ can be equal or different), and swaps the characters $$$s_i$$$ and $$$t_j$$$.Ujan's goal is to make the strings $$$s$$$ and $$$t$$$ equal. He does not need to minimize the number of performed operations: any sequence of operations of length $$$2n$$$ or shorter is suitable.",['strings']903"Adilbek's house is located on a street which can be represented as the OX axis. This street is really dark, so Adilbek wants to install some post lamps to illuminate it. Street has $$$n$$$ positions to install lamps, they correspond to the integer numbers from $$$0$$$ to $$$n - 1$$$ on the OX axis. However, some positions are blocked and no post lamp can be placed there.There are post lamps of different types which differ only by their power. When placed in position $$$x$$$, post lamp of power $$$l$$$ illuminates the segment $$$[x; x + l]$$$. The power of each post lamp is always a positive integer number.The post lamp shop provides an infinite amount of lamps of each type from power $$$1$$$ to power $$$k$$$. Though each customer is only allowed to order post lamps of exactly one type. Post lamps of power $$$l$$$ cost $$$a_l$$$ each.What is the minimal total cost of the post lamps of exactly one type Adilbek can buy to illuminate the entire segment $$$[0; n]$$$ of the street? If some lamps illuminate any other segment of the street, Adilbek does not care, so, for example, he may place a lamp of power $$$3$$$ in position $$$n - 1$$$ (even though its illumination zone doesn't completely belong to segment $$$[0; n]$$$).",[]904"You are given an n × m rectangular table consisting of lower case English letters. In one operation you can completely remove one column from the table. The remaining parts are combined forming a new table. For example, after removing the second column from the tableabcdedfghijk we obtain the table:acdefghjk A table is called good if its rows are ordered from top to bottom lexicographically, i.e. each row is lexicographically no larger than the following one. Determine the minimum number of operations of removing a column needed to make a given table good.",[]905"Iahub likes trees very much. Recently he discovered an interesting tree named propagating tree. The tree consists of n nodes numbered from 1 to n, each node i having an initial value ai. The root of the tree is node 1.This tree has a special property: when a value val is added to a value of node i, the value -val is added to values of all the children of node i. Note that when you add value -val to a child of node i, you also add -(-val) to all children of the child of node i and so on. Look an example explanation to understand better how it works.This tree supports two types of queries:  ""1 x val"" — val is added to the value of node x;  ""2 x"" — print the current value of node x. In order to help Iahub understand the tree better, you must answer m queries of the preceding type.",['trees']906"Vasya became interested in bioinformatics. He's going to write an article about similar cyclic DNA sequences, so he invented a new method for determining the similarity of cyclic sequences.Let's assume that strings s and t have the same length n, then the function h(s, t) is defined as the number of positions in which the respective symbols of s and t are the same. Function h(s, t) can be used to define the function of Vasya distance ρ(s, t):  where  is obtained from string s, by applying left circular shift i times. For example, ρ(""AGC"", ""CGT"") =  h(""AGC"", ""CGT"") + h(""AGC"", ""GTC"") + h(""AGC"", ""TCG"") +  h(""GCA"", ""CGT"") + h(""GCA"", ""GTC"") + h(""GCA"", ""TCG"") +  h(""CAG"", ""CGT"") + h(""CAG"", ""GTC"") + h(""CAG"", ""TCG"") =  1 + 1 + 0 + 0 + 1 + 1 + 1 + 0 + 1 = 6Vasya found a string s of length n on the Internet. Now he wants to count how many strings t there are such that the Vasya distance from the string s attains maximum possible value. Formally speaking, t must satisfy the equation: .Vasya could not try all possible strings to find an answer, so he needs your help. As the answer may be very large, count the number of such strings modulo 109 + 7.","['math', 'strings']"907"SaMer has written the greatest test case of all time for one of his problems. For a given array of integers, the problem asks to find the minimum number of groups the array can be divided into, such that the product of any pair of integers in the same group is a perfect square. Each integer must be in exactly one group. However, integers in a group do not necessarily have to be contiguous in the array.SaMer wishes to create more cases from the test case he already has. His test case has an array $$$A$$$ of $$$n$$$ integers, and he needs to find the number of contiguous subarrays of $$$A$$$ that have an answer to the problem equal to $$$k$$$ for each integer $$$k$$$ between $$$1$$$ and $$$n$$$ (inclusive).","['math', 'number theory']"908"You are given a tree consisting of $$$n$$$ vertices. Recall that a tree is an undirected connected acyclic graph. The given tree is rooted at the vertex $$$1$$$.You have to process $$$q$$$ queries. In each query, you are given a vertex of the tree $$$v$$$ and an integer $$$k$$$.To process a query, you may delete any vertices from the tree in any order, except for the root and the vertex $$$v$$$. When a vertex is deleted, its children become the children of its parent. You have to process a query in such a way that maximizes the value of $$$c(v) - m \cdot k$$$ (where $$$c(v)$$$ is the resulting number of children of the vertex $$$v$$$, and $$$m$$$ is the number of vertices you have deleted). Print the maximum possible value you can obtain.The queries are independent: the changes you make to the tree while processing a query don't affect the tree in other queries.",['trees']909"Salem gave you $$$n$$$ sticks with integer positive lengths $$$a_1, a_2, \ldots, a_n$$$.For every stick, you can change its length to any other positive integer length (that is, either shrink or stretch it). The cost of changing the stick's length from $$$a$$$ to $$$b$$$ is $$$|a - b|$$$, where $$$|x|$$$ means the absolute value of $$$x$$$.A stick length $$$a_i$$$ is called almost good for some integer $$$t$$$ if $$$|a_i - t| \le 1$$$.Salem asks you to change the lengths of some sticks (possibly all or none), such that all sticks' lengths are almost good for some positive integer $$$t$$$ and the total cost of changing is minimum possible. The value of $$$t$$$ is not fixed in advance and you can choose it as any positive integer. As an answer, print the value of $$$t$$$ and the minimum cost. If there are multiple optimal choices for $$$t$$$, print any of them.",[]910"You are given n integers a1, a2, ..., an. Find the number of pairs of indexes i, j (i < j) that ai + aj is a power of 2 (i. e. some integer x exists so that ai + aj = 2x).",['math']911"The secondary diagonal of a square matrix is a diagonal going from the top right to the bottom left corner. Let's define an n-degree staircase as a square matrix n × n containing no squares above the secondary diagonal (the picture below shows a 5-degree staircase).   The squares of the n-degree staircase contain m sportsmen. A sportsman needs one second to move to a side-neighboring square of the staircase. Before the beginning of the competition each sportsman must choose one of the shortest ways to the secondary diagonal. After the starting whistle the competition begins and all sportsmen start moving along the chosen paths. When a sportsman reaches a cell of the secondary diagonal, he stops and moves no more. The competition ends when all sportsmen reach the secondary diagonal. The competition is considered successful if during it no two sportsmen were present in the same square simultaneously. Any square belonging to the secondary diagonal also cannot contain more than one sportsman. If a sportsman at the given moment of time leaves a square and another sportsman comes to it, then they are not considered to occupy the same square simultaneously. Note that other extreme cases (for example, two sportsmen moving towards each other) are impossible as the chosen ways are the shortest ones.You are given positions of m sportsmen on the staircase. Your task is to choose among them the maximum number of sportsmen for who the competition can be successful, that is, so that there existed such choice of shortest ways for the sportsmen at which no two sportsmen find themselves in the same square simultaneously. All other sportsmen that are not chosen will be removed from the staircase before the competition starts. ",[]912"Let's call a positive integer composite if it has at least one divisor other than $$$1$$$ and itself. For example:  the following numbers are composite: $$$1024$$$, $$$4$$$, $$$6$$$, $$$9$$$;  the following numbers are not composite: $$$13$$$, $$$1$$$, $$$2$$$, $$$3$$$, $$$37$$$. You are given a positive integer $$$n$$$. Find two composite integers $$$a,b$$$ such that $$$a-b=n$$$.It can be proven that solution always exists.",['math']913"You are running through a rectangular field. This field can be represented as a matrix with 3 rows and m columns. (i, j) denotes a cell belonging to i-th row and j-th column.You start in (2, 1) and have to end your path in (2, m). From the cell (i, j) you may advance to:  (i - 1, j + 1) — only if i > 1,  (i, j + 1), or  (i + 1, j + 1) — only if i < 3. However, there are n obstacles blocking your path. k-th obstacle is denoted by three integers ak, lk and rk, and it forbids entering any cell (ak, j) such that lk ≤ j ≤ rk.You have to calculate the number of different paths from (2, 1) to (2, m), and print it modulo 109 + 7.",[]914"There are $$$n$$$ children, who study at the school №41. It is well-known that they are good mathematicians. Once at a break, they arranged a challenge for themselves. All children arranged in a row and turned heads either to the left or to the right.Children can do the following: in one second several pairs of neighboring children who are looking at each other can simultaneously turn the head in the opposite direction. For instance, the one who was looking at the right neighbor turns left and vice versa for the second child. Moreover, every second at least one pair of neighboring children performs such action. They are going to finish when there is no pair of neighboring children who are looking at each other. You are given the number $$$n$$$, the initial arrangement of children and the number $$$k$$$. You have to find a way for the children to act if they want to finish the process in exactly $$$k$$$ seconds. More formally, for each of the $$$k$$$ moves, you need to output the numbers of the children who turn left during this move.For instance, for the configuration shown below and $$$k = 2$$$ children can do the following steps:    At the beginning, two pairs make move: $$$(1, 2)$$$ and $$$(3, 4)$$$. After that, we receive the following configuration:    At the second move pair $$$(2, 3)$$$ makes the move. The final configuration is reached. Good job.   It is guaranteed that if the solution exists, it takes not more than $$$n^2$$$ ""headturns"".","['graphs', 'games']"915"Now that Heidi has made sure her Zombie Contamination level checker works, it's time to strike! This time, the zombie lair is a strictly convex polygon on the lattice. Each vertex of the polygon occupies a point on the lattice. For each cell of the lattice, Heidi knows the level of Zombie Contamination – the number of corners of the cell that are inside or on the border of the lair.Given this information, Heidi wants to know the exact shape of the lair to rain destruction on the zombies. Help her!",['geometry']916"Since Sonya is interested in robotics too, she decided to construct robots that will read and recognize numbers.Sonya has drawn $$$n$$$ numbers in a row, $$$a_i$$$ is located in the $$$i$$$-th position. She also has put a robot at each end of the row (to the left of the first number and to the right of the last number). Sonya will give a number to each robot (they can be either same or different) and run them. When a robot is running, it is moving toward to another robot, reading numbers in the row. When a robot is reading a number that is equal to the number that was given to that robot, it will turn off and stay in the same position.Sonya does not want robots to break, so she will give such numbers that robots will stop before they meet. That is, the girl wants them to stop at different positions so that the first robot is to the left of the second one.For example, if the numbers $$$[1, 5, 4, 1, 3]$$$ are written, and Sonya gives the number $$$1$$$ to the first robot and the number $$$4$$$ to the second one, the first robot will stop in the $$$1$$$-st position while the second one in the $$$3$$$-rd position. In that case, robots will not meet each other. As a result, robots will not be broken. But if Sonya gives the number $$$4$$$ to the first robot and the number $$$5$$$ to the second one, they will meet since the first robot will stop in the $$$3$$$-rd position while the second one is in the $$$2$$$-nd position.Sonya understands that it does not make sense to give a number that is not written in the row because a robot will not find this number and will meet the other robot.Sonya is now interested in finding the number of different pairs that she can give to robots so that they will not meet. In other words, she wants to know the number of pairs ($$$p$$$, $$$q$$$), where she will give $$$p$$$ to the first robot and $$$q$$$ to the second one. Pairs ($$$p_i$$$, $$$q_i$$$) and ($$$p_j$$$, $$$q_j$$$) are different if $$$p_i\neq p_j$$$ or $$$q_i\neq q_j$$$.Unfortunately, Sonya is busy fixing robots that broke after a failed launch. That is why she is asking you to find the number of pairs that she can give to robots so that they will not meet.",[]917"Unfortunately, Vasya can only sum pairs of integers (a, b), such that for any decimal place at least one number has digit 0 in this place. For example, Vasya can sum numbers 505 and 50, but he cannot sum 1 and 4.Vasya has a set of k distinct non-negative integers d1, d2, ..., dk.Vasya wants to choose some integers from this set so that he could sum any two chosen numbers. What maximal number of integers can he choose in the required manner?",[]918"Recently, on the course of algorithms and data structures, Valeriy learned how to use a deque. He built a deque filled with $$$n$$$ elements. The $$$i$$$-th element is $$$a_i$$$ ($$$i$$$ = $$$1, 2, \ldots, n$$$). He gradually takes the first two leftmost elements from the deque (let's call them $$$A$$$ and $$$B$$$, respectively), and then does the following: if $$$A > B$$$, he writes $$$A$$$ to the beginning and writes $$$B$$$ to the end of the deque, otherwise, he writes to the beginning $$$B$$$, and $$$A$$$ writes to the end of the deque. We call this sequence of actions an operation.For example, if deque was $$$[2, 3, 4, 5, 1]$$$, on the operation he will write $$$B=3$$$ to the beginning and $$$A=2$$$ to the end, so he will get $$$[3, 4, 5, 1, 2]$$$.The teacher of the course, seeing Valeriy, who was passionate about his work, approached him and gave him $$$q$$$ queries. Each query consists of the singular number $$$m_j$$$ $$$(j = 1, 2, \ldots, q)$$$. It is required for each query to answer which two elements he will pull out on the $$$m_j$$$-th operation.Note that the queries are independent and for each query the numbers $$$A$$$ and $$$B$$$ should be printed in the order in which they will be pulled out of the deque.Deque is a data structure representing a list of elements where insertion of new elements or deletion of existing elements can be made from both sides.",[]919"You have a given picture with size $$$w \times h$$$. Determine if the given picture has a single ""+"" shape or not. A ""+"" shape is described below:  A ""+"" shape has one center nonempty cell.  There should be some (at least one) consecutive non-empty cells in each direction (left, right, up, down) from the center. In other words, there should be a ray in each direction.  All other cells are empty. Find out if the given picture has single ""+"" shape.",['strings']920"You are the gym teacher in the school.There are $$$n$$$ students in the row. And there are two rivalling students among them. The first one is in position $$$a$$$, the second in position $$$b$$$. Positions are numbered from $$$1$$$ to $$$n$$$ from left to right.Since they are rivals, you want to maximize the distance between them. If students are in positions $$$p$$$ and $$$s$$$ respectively, then distance between them is $$$|p - s|$$$. You can do the following operation at most $$$x$$$ times: choose two adjacent (neighbouring) students and swap them.Calculate the maximum distance between two rivalling students after at most $$$x$$$ swaps.",['math']921"Miyako came to the flea kingdom with a ukulele. She became good friends with local flea residents and played beautiful music for them every day.In return, the fleas made a bigger ukulele for her: it has $$$n$$$ strings, and each string has $$$(10^{18} + 1)$$$ frets numerated from $$$0$$$ to $$$10^{18}$$$. The fleas use the array $$$s_1, s_2, \ldots, s_n$$$ to describe the ukulele's tuning, that is, the pitch of the $$$j$$$-th fret on the $$$i$$$-th string is the integer $$$s_i + j$$$.Miyako is about to leave the kingdom, but the fleas hope that Miyako will answer some last questions for them.Each question is in the form of: ""How many different pitches are there, if we consider frets between $$$l$$$ and $$$r$$$ (inclusive) on all strings?""Miyako is about to visit the cricket kingdom and has no time to answer all the questions. Please help her with this task!Formally, you are given a matrix with $$$n$$$ rows and $$$(10^{18}+1)$$$ columns, where the cell in the $$$i$$$-th row and $$$j$$$-th column ($$$0 \le j \le 10^{18}$$$) contains the integer $$$s_i + j$$$. You are to answer $$$q$$$ queries, in the $$$k$$$-th query you have to answer the number of distinct integers in the matrix from the $$$l_k$$$-th to the $$$r_k$$$-th columns, inclusive.",[]922"Malek has recently found a treasure map. While he was looking for a treasure he found a locked door. There was a string s written on the door consisting of characters '(', ')' and '#'. Below there was a manual on how to open the door. After spending a long time Malek managed to decode the manual and found out that the goal is to replace each '#' with one or more ')' characters so that the final string becomes beautiful. Below there was also written that a string is called beautiful if for each i (1 ≤ i ≤ |s|) there are no more ')' characters than '(' characters among the first i characters of s and also the total number of '(' characters is equal to the total number of ')' characters. Help Malek open the door by telling him for each '#' character how many ')' characters he must replace it with.",[]923"Because of budget cuts one IT company established new non-financial reward system instead of bonuses.Two kinds of actions are rewarded: fixing critical bugs and suggesting new interesting features. A man who fixed a critical bug gets ""I fixed a critical bug"" pennant on his table. A man who suggested a new interesting feature gets ""I suggested a new feature"" pennant on his table.Because of the limited budget of the new reward system only 5 ""I fixed a critical bug"" pennants and 3 ""I suggested a new feature"" pennants were bought.In order to use these pennants for a long time they were made challenge ones. When a man fixes a new critical bug one of the earlier awarded ""I fixed a critical bug"" pennants is passed on to his table. When a man suggests a new interesting feature one of the earlier awarded ""I suggested a new feature"" pennants is passed on to his table.One man can have several pennants of one type and of course he can have pennants of both types on his table. There are n tables in the IT company. Find the number of ways to place the pennants on these tables given that each pennant is situated on one of the tables and each table is big enough to contain any number of pennants.",['math']924"Andi and Budi were given an assignment to tidy up their bookshelf of $$$n$$$ books. Each book is represented by the book title — a string $$$s_i$$$ numbered from $$$1$$$ to $$$n$$$, each with length $$$m$$$. Andi really wants to sort the book lexicographically ascending, while Budi wants to sort it lexicographically descending.Settling their fight, they decided to combine their idea and sort it asc-desc-endingly, where the odd-indexed characters will be compared ascendingly, and the even-indexed characters will be compared descendingly.A string $$$a$$$ occurs before a string $$$b$$$ in asc-desc-ending order if and only if in the first position where $$$a$$$ and $$$b$$$ differ, the following holds:  if it is an odd position, the string $$$a$$$ has a letter that appears earlier in the alphabet than the corresponding letter in $$$b$$$;  if it is an even position, the string $$$a$$$ has a letter that appears later in the alphabet than the corresponding letter in $$$b$$$. ",['strings']925"You are given an array of $$$n$$$ integers $$$a_1, a_2, \ldots, a_n$$$. After you watched the amazing film ""Everything Everywhere All At Once"", you came up with the following operation.In one operation, you choose $$$n-1$$$ elements of the array and replace each of them with their arithmetic mean (which doesn't have to be an integer). For example, from the array $$$[1, 2, 3, 1]$$$ we can get the array $$$[2, 2, 2, 1]$$$, if we choose the first three elements, or we can get the array $$$[\frac{4}{3}, \frac{4}{3}, 3, \frac{4}{3}]$$$, if we choose all elements except the third.Is it possible to make all elements of the array equal by performing a finite number of such operations?",[]926"Dima worked all day and wrote down on a long paper strip his favorite number $$$n$$$ consisting of $$$l$$$ digits. Unfortunately, the strip turned out to be so long that it didn't fit in the Dima's bookshelf.To solve the issue, Dima decided to split the strip into two non-empty parts so that each of them contains a positive integer without leading zeros. After that he will compute the sum of the two integers and write it down on a new strip.Dima wants the resulting integer to be as small as possible, because it increases the chances that the sum will fit it in the bookshelf. Help Dima decide what is the minimum sum he can obtain.",['strings']927"You are given a text that consists of lowercase Latin letters, spaces and punctuation marks (dot, comma, exclamation mark and question mark). A word is defined as a sequence of consecutive Latin letters.Your task is to add spaces to the text by the following rules:  if there is no punctuation mark between two words, then they should be separated by exactly one space  there should be no spaces before each punctuation mark  there should be exactly one space after each punctuation mark It is guaranteed that there is at least one word between any two punctuation marks. The text begins and ends with a Latin letter.",['strings']928"You have a square chessboard of size $$$n \times n$$$. Rows are numbered from top to bottom with numbers from $$$1$$$ to $$$n$$$, and columns — from left to right with numbers from $$$1$$$ to $$$n$$$. So, each cell is denoted with pair of integers $$$(x, y)$$$ ($$$1 \le x, y \le n$$$), where $$$x$$$ is a row number and $$$y$$$ is a column number.You have to perform $$$q$$$ queries of three types:  Put a new rook in cell $$$(x, y)$$$.  Remove a rook from cell $$$(x, y)$$$. It's guaranteed that the rook was put in this cell before.  Check if each cell of subrectangle $$$(x_1, y_1) - (x_2, y_2)$$$ of the board is attacked by at least one rook. Subrectangle is a set of cells $$$(x, y)$$$ such that for each cell two conditions are satisfied: $$$x_1 \le x \le x_2$$$ and $$$y_1 \le y \le y_2$$$.Recall that cell $$$(a, b)$$$ is attacked by a rook placed in cell $$$(c, d)$$$ if either $$$a = c$$$ or $$$b = d$$$. In particular, the cell containing a rook is attacked by this rook.",[]929"Masha meets a new friend and learns his phone number — $$$s$$$. She wants to remember it as soon as possible. The phone number — is a string of length $$$m$$$ that consists of digits from $$$0$$$ to $$$9$$$. The phone number may start with 0.Masha already knows $$$n$$$ phone numbers (all numbers have the same length $$$m$$$). It will be easier for her to remember a new number if the $$$s$$$ is represented as segments of numbers she already knows. Each such segment must be of length at least $$$2$$$, otherwise there will be too many segments and Masha will get confused.For example, Masha needs to remember the number: $$$s = $$$ '12345678' and she already knows $$$n = 4$$$ numbers: '12340219', '20215601', '56782022', '12300678'. You can represent $$$s$$$ as a $$$3$$$ segment: '1234' of number one, '56' of number two, and '78' of number three. There are other ways to represent $$$s$$$.Masha asks you for help, she asks you to break the string $$$s$$$ into segments of length $$$2$$$ or more of the numbers she already knows. If there are several possible answers, print any of them.",['strings']930"Billy investigates the question of applying greedy algorithm to different spheres of life. At the moment he is studying the application of greedy algorithm to the problem about change. There is an amount of n coins of different face values, and the coins of each value are not limited in number. The task is to collect the sum x with the minimum amount of coins. Greedy algorithm with each its step takes the coin of the highest face value, not exceeding x. Obviously, if among the coins' face values exists the face value 1, any sum x can be collected with the help of greedy algorithm. However, greedy algorithm does not always give the optimal representation of the sum, i.e. the representation with the minimum amount of coins. For example, if there are face values {1, 3, 4} and it is asked to collect the sum 6, greedy algorithm will represent the sum as 4 + 1 + 1, while the optimal representation is 3 + 3, containing one coin less. By the given set of face values find out if there exist such a sum x that greedy algorithm will collect in a non-optimal way. If such a sum exists, find out the smallest of these sums.",[]931"There are n problems prepared for the next Codeforces round. They are arranged in ascending order by their difficulty, and no two problems have the same difficulty. Moreover, there are m pairs of similar problems. Authors want to split problems between two division according to the following rules:   Problemset of each division should be non-empty.  Each problem should be used in exactly one division (yes, it is unusual requirement).  Each problem used in division 1 should be harder than any problem used in division 2.  If two problems are similar, they should be used in different divisions. Your goal is count the number of ways to split problem between two divisions and satisfy all the rules. Two ways to split problems are considered to be different if there is at least one problem that belongs to division 1 in one of them and to division 2 in the other.Note, that the relation of similarity is not transitive. That is, if problem i is similar to problem j and problem j is similar to problem k, it doesn't follow that i is similar to k.",[]932"Tavas is a cheerleader in the new sports competition named ""Pashmaks"".  This competition consists of two part: swimming and then running. People will immediately start running R meters after they finished swimming exactly S meters. A winner is a such person that nobody else finishes running before him/her (there may be more than one winner).Before the match starts, Tavas knows that there are n competitors registered for the match. Also, he knows that i-th person's swimming speed is si meters per second and his/her running speed is ri meters per second. Unfortunately, he doesn't know the values of R and S, but he knows that they are real numbers greater than 0.As a cheerleader, Tavas wants to know who to cheer up. So, he wants to know all people that might win. We consider a competitor might win if and only if there are some values of R and S such that with these values, (s)he will be a winner.Tavas isn't really familiar with programming, so he asked you to help him.","['math', 'geometry']"933"Berland is going through tough times — the dirt price has dropped and that is a blow to the country's economy. Everybody knows that Berland is the top world dirt exporter!The President of Berland was forced to leave only k of the currently existing n subway stations.The subway stations are located on a straight line one after another, the trains consecutively visit the stations as they move. You can assume that the stations are on the Ox axis, the i-th station is at point with coordinate xi. In such case the distance between stations i and j is calculated by a simple formula |xi - xj|.Currently, the Ministry of Transport is choosing which stations to close and which ones to leave. Obviously, the residents of the capital won't be too enthusiastic about the innovation, so it was decided to show the best side to the people. The Ministry of Transport wants to choose such k stations that minimize the average commute time in the subway!Assuming that the train speed is constant (it is a fixed value), the average commute time in the subway is calculated as the sum of pairwise distances between stations, divided by the number of pairs (that is ) and divided by the speed of the train.Help the Minister of Transport to solve this difficult problem. Write a program that, given the location of the stations selects such k stations that the average commute time in the subway is minimized.",['math']934"There are n parliamentarians in Berland. They are numbered with integers from 1 to n. It happened that all parliamentarians with odd indices are Democrats and all parliamentarians with even indices are Republicans.New parliament assembly hall is a rectangle consisting of a × b chairs — a rows of b chairs each. Two chairs are considered neighbouring if they share as side. For example, chair number 5 in row number 2 is neighbouring to chairs number 4 and 6 in this row and chairs with number 5 in rows 1 and 3. Thus, chairs have four neighbours in general, except for the chairs on the border of the hallWe know that if two parliamentarians from one political party (that is two Democrats or two Republicans) seat nearby they spent all time discussing internal party issues.Write the program that given the number of parliamentarians and the sizes of the hall determine if there is a way to find a seat for any parliamentarian, such that no two members of the same party share neighbouring seats.",[]935"This is the easy version of the problem. The only difference is that in this version $$$n \leq 2000$$$. You can make hacks only if both versions of the problem are solved.There are $$$n$$$ potions in a line, with potion $$$1$$$ on the far left and potion $$$n$$$ on the far right. Each potion will increase your health by $$$a_i$$$ when drunk. $$$a_i$$$ can be negative, meaning that potion will decrease will health.You start with $$$0$$$ health and you will walk from left to right, from first potion to the last one. At each potion, you may choose to drink it or ignore it. You must ensure that your health is always non-negative.What is the largest number of potions you can drink?",[]936"You have unweighted tree of $$$n$$$ vertices. You have to assign a positive weight to each edge so that the following condition would hold:  For every two different leaves $$$v_{1}$$$ and $$$v_{2}$$$ of this tree, bitwise XOR of weights of all edges on the simple path between $$$v_{1}$$$ and $$$v_{2}$$$ has to be equal to $$$0$$$. Note that you can put very large positive integers (like $$$10^{(10^{10})}$$$).It's guaranteed that such assignment always exists under given constraints. Now let's define $$$f$$$ as the number of distinct weights in assignment.  In this example, assignment is valid, because bitwise XOR of all edge weights between every pair of leaves is $$$0$$$. $$$f$$$ value is $$$2$$$ here, because there are $$$2$$$ distinct edge weights($$$4$$$ and $$$5$$$). In this example, assignment is invalid, because bitwise XOR of all edge weights between vertex $$$1$$$ and vertex $$$6$$$ ($$$3, 4, 5, 4$$$) is not $$$0$$$. What are the minimum and the maximum possible values of $$$f$$$ for the given tree? Find and print both.",['trees']937"Vasya has an array a consisting of positive integer numbers. Vasya wants to divide this array into two non-empty consecutive parts (the prefix and the suffix) so that the sum of all elements in the first part equals to the sum of elements in the second part. It is not always possible, so Vasya will move some element before dividing the array (Vasya will erase some element and insert it into an arbitrary position).Inserting an element in the same position he was erased from is also considered moving.Can Vasya divide the array after choosing the right element to move and its new position?",[]938"Berland regional ICPC contest has just ended. There were $$$m$$$ participants numbered from $$$1$$$ to $$$m$$$, who competed on a problemset of $$$n$$$ problems numbered from $$$1$$$ to $$$n$$$.Now the editorial is about to take place. There are two problem authors, each of them is going to tell the tutorial to exactly $$$k$$$ consecutive tasks of the problemset. The authors choose the segment of $$$k$$$ consecutive tasks for themselves independently of each other. The segments can coincide, intersect or not intersect at all.The $$$i$$$-th participant is interested in listening to the tutorial of all consecutive tasks from $$$l_i$$$ to $$$r_i$$$. Each participant always chooses to listen to only the problem author that tells the tutorials to the maximum number of tasks he is interested in. Let this maximum number be $$$a_i$$$. No participant can listen to both of the authors, even if their segments don't intersect.The authors want to choose the segments of $$$k$$$ consecutive tasks for themselves in such a way that the sum of $$$a_i$$$ over all participants is maximized.",[]939"Note that the only difference between the easy and hard version is the constraint on the number of queries. You can make hacks only if all versions of the problem are solved.This is an interactive problem.You are given a tree consisting of $$$n$$$ nodes numbered with integers from $$$1$$$ to $$$n$$$. Ayush and Ashish chose two secret distinct nodes in the tree. You need to find out both the nodes. You can make the following query:   Provide a list of nodes and you will receive a node from that list whose sum of distances to both the hidden nodes is minimal (if there are multiple such nodes in the list, you will receive any one of them). You will also get the sum of distances of that node to the hidden nodes. Recall that a tree is a connected graph without cycles. The distance between two nodes is defined as the number of edges in the simple path between them.More formally, let's define two hidden nodes as $$$s$$$ and $$$f$$$. In one query you can provide the set of nodes $$$\{a_1, a_2, \ldots, a_c\}$$$ of the tree. As a result, you will get two numbers $$$a_i$$$ and $$$dist(a_i, s) + dist(a_i, f)$$$. The node $$$a_i$$$ is any node from the provided set, for which the number $$$dist(a_i, s) + dist(a_i, f)$$$ is minimal.You can ask no more than $$$14$$$ queries.","['graphs', 'trees']"940"Developers often face with regular expression patterns. A pattern is usually defined as a string consisting of characters and metacharacters that sets the rules for your search. These patterns are most often used to check whether a particular string meets the certain rules.In this task, a pattern will be a string consisting of small English letters and question marks ('?'). The question mark in the pattern is a metacharacter that denotes an arbitrary small letter of the English alphabet. We will assume that a string matches the pattern if we can transform the string into the pattern by replacing the question marks by the appropriate characters. For example, string aba matches patterns: ???, ??a, a?a, aba.Programmers that work for the R1 company love puzzling each other (and themselves) with riddles. One of them is as follows: you are given n patterns of the same length, you need to find a pattern that contains as few question marks as possible, and intersects with each of the given patterns. Two patterns intersect if there is a string that matches both the first and the second pattern. Can you solve this riddle?",['strings']941"Rikhail Mubinchik believes that the current definition of prime numbers is obsolete as they are too complex and unpredictable. A palindromic number is another matter. It is aesthetically pleasing, and it has a number of remarkable properties. Help Rikhail to convince the scientific community in this!Let us remind you that a number is called prime if it is integer larger than one, and is not divisible by any positive integer other than itself and one.Rikhail calls a number a palindromic if it is integer, positive, and its decimal representation without leading zeros is a palindrome, i.e. reads the same from left to right and right to left.One problem with prime numbers is that there are too many of them. Let's introduce the following notation: π(n) — the number of primes no larger than n, rub(n) — the number of palindromic numbers no larger than n. Rikhail wants to prove that there are a lot more primes than palindromic ones.He asked you to solve the following problem: for a given value of the coefficient A find the maximum n, such that π(n) ≤ A·rub(n).","['math', 'number theory']"942"You are given $$$n$$$ points on the plane, the coordinates of the $$$i$$$-th point are $$$(x_i, y_i)$$$. No two points have the same coordinates.The distance between points $$$i$$$ and $$$j$$$ is defined as $$$d(i,j) = |x_i - x_j| + |y_i - y_j|$$$.For each point, you have to choose a color, represented by an integer from $$$1$$$ to $$$n$$$. For every ordered triple of different points $$$(a,b,c)$$$, the following constraints should be met:  if $$$a$$$, $$$b$$$ and $$$c$$$ have the same color, then $$$d(a,b) = d(a,c) = d(b,c)$$$;  if $$$a$$$ and $$$b$$$ have the same color, and the color of $$$c$$$ is different from the color of $$$a$$$, then $$$d(a,b) < d(a,c)$$$ and $$$d(a,b) < d(b,c)$$$. Calculate the number of different ways to choose the colors that meet these constraints.","['math', 'graphs', 'geometry']"943"A remote island chain contains n islands, labeled 1 through n. Bidirectional bridges connect the islands to form a simple cycle — a bridge connects islands 1 and 2, islands 2 and 3, and so on, and additionally a bridge connects islands n and 1. The center of each island contains an identical pedestal, and all but one of the islands has a fragile, uniquely colored statue currently held on the pedestal. The remaining island holds only an empty pedestal.The islanders want to rearrange the statues in a new order. To do this, they repeat the following process: First, they choose an island directly adjacent to the island containing an empty pedestal. Then, they painstakingly carry the statue on this island across the adjoining bridge and place it on the empty pedestal.Determine if it is possible for the islanders to arrange the statues in the desired order.",[]944"At the store, the salespeople want to make all prices round. In this problem, a number that is a power of $$$10$$$ is called a round number. For example, the numbers $$$10^0 = 1$$$, $$$10^1 = 10$$$, $$$10^2 = 100$$$ are round numbers, but $$$20$$$, $$$110$$$ and $$$256$$$ are not round numbers. So, if an item is worth $$$m$$$ bourles (the value of the item is not greater than $$$10^9$$$), the sellers want to change its value to the nearest round number that is not greater than $$$m$$$. They ask you: by how many bourles should you decrease the value of the item to make it worth exactly $$$10^k$$$ bourles, where the value of $$$k$$$ — is the maximum possible ($$$k$$$ — any non-negative integer).For example, let the item have a value of $$$178$$$-bourles. Then the new price of the item will be $$$100$$$, and the answer will be $$$178-100=78$$$.",[]945"One day, after a difficult lecture a diligent student Sasha saw a graffitied desk in the classroom. She came closer and read: ""Find such positive integer n, that among numbers n + 1, n + 2, ..., 2·n there are exactly m numbers which binary representation contains exactly k digits one"".The girl got interested in the task and she asked you to help her solve it. Sasha knows that you are afraid of large numbers, so she guaranteed that there is an answer that doesn't exceed 1018.",['math']946"As the guys fried the radio station facilities, the school principal gave them tasks as a punishment. Dustin's task was to add comments to nginx configuration for school's website. The school has n servers. Each server has a name and an ip (names aren't necessarily unique, but ips are). Dustin knows the ip and name of each server. For simplicity, we'll assume that an nginx command is of form ""command ip;"" where command is a string consisting of English lowercase letter only, and ip is the ip of one of school servers.  Each ip is of form ""a.b.c.d"" where a, b, c and d are non-negative integers less than or equal to 255 (with no leading zeros). The nginx configuration file Dustin has to add comments to has m commands. Nobody ever memorizes the ips of servers, so to understand the configuration better, Dustin has to comment the name of server that the ip belongs to at the end of each line (after each command). More formally, if a line is ""command ip;"" Dustin has to replace it with ""command ip; #name"" where name is the name of the server with ip equal to ip.Dustin doesn't know anything about nginx, so he panicked again and his friends asked you to do his task for him.",['strings']947"You are given an integer $$$n$$$. Find any string $$$s$$$ of length $$$n$$$ consisting only of English lowercase letters such that each non-empty substring of $$$s$$$ occurs in $$$s$$$ an odd number of times. If there are multiple such strings, output any. It can be shown that such string always exists under the given constraints.A string $$$a$$$ is a substring of a string $$$b$$$ if $$$a$$$ can be obtained from $$$b$$$ by deletion of several (possibly, zero or all) characters from the beginning and several (possibly, zero or all) characters from the end.",['strings']948"Dima, Inna and Seryozha have gathered in a room. That's right, someone's got to go. To cheer Seryozha up and inspire him to have a walk, Inna decided to cook something. Dima and Seryozha have n fruits in the fridge. Each fruit has two parameters: the taste and the number of calories. Inna decided to make a fruit salad, so she wants to take some fruits from the fridge for it. Inna follows a certain principle as she chooses the fruits: the total taste to the total calories ratio of the chosen fruits must equal k. In other words,  , where aj is the taste of the j-th chosen fruit and bj is its calories.Inna hasn't chosen the fruits yet, she is thinking: what is the maximum taste of the chosen fruits if she strictly follows her principle? Help Inna solve this culinary problem — now the happiness of a young couple is in your hands!Inna loves Dima very much so she wants to make the salad from at least one fruit.",[]949"There is a grid with $$$n$$$ rows and $$$m$$$ columns, and three types of cells:   An empty cell, denoted with '.'.  A stone, denoted with '*'.  An obstacle, denoted with the lowercase Latin letter 'o'. All stones fall down until they meet the floor (the bottom row), an obstacle, or other stone which is already immovable. (In other words, all the stones just fall down as long as they can fall.)Simulate the process. What does the resulting grid look like?",[]950"Most C/C++ programmers know about excellent opportunities that preprocessor #define directives give; but many know as well about the problems that can arise because of their careless use.In this problem we consider the following model of #define constructions (also called macros). Each macro has its name and value. The generic syntax for declaring a macro is the following:#define macro_name macro_valueAfter the macro has been declared, ""macro_name"" is replaced with ""macro_value"" each time it is met in the program (only the whole tokens can be replaced; i.e. ""macro_name"" is replaced only when it is surrounded by spaces or other non-alphabetic symbol). A ""macro_value"" within our model can only be an arithmetic expression consisting of variables, four arithmetic operations, brackets, and also the names of previously declared macros (in this case replacement is performed sequentially). The process of replacing macros with their values is called substitution.One of the main problems arising while using macros — the situation when as a result of substitution we get an arithmetic expression with the changed order of calculation because of different priorities of the operations.Let's consider the following example. Say, we declared such a #define construction:#define sum x + yand further in the program the expression ""2 * sum"" is calculated. After macro substitution is performed we get ""2 * x + y"", instead of intuitively expected ""2 * (x + y)"".Let's call the situation ""suspicious"", if after the macro substitution the order of calculation changes, falling outside the bounds of some macro. Thus, your task is to find out by the given set of #define definitions and the given expression if this expression is suspicious or not.Let's speak more formally. We should perform an ordinary macros substitution in the given expression. Moreover, we should perform a ""safe"" macros substitution in the expression, putting in brackets each macro value; after this, guided by arithmetic rules of brackets expansion, we can omit some of the brackets. If there exist a way to get an expression, absolutely coinciding with the expression that is the result of an ordinary substitution (character-by-character, but ignoring spaces), then this expression and the macros system are called correct, otherwise — suspicious.Note that we consider the ""/"" operation as the usual mathematical division, not the integer division like in C/C++. That's why, for example, in the expression ""a*(b/c)"" we can omit brackets to get the expression ""a*b/c"".",[]951"One day Alice was cleaning up her basement when she noticed something very curious: an infinite set of wooden pieces! Each piece was made of five square tiles, with four tiles adjacent to the fifth center tile:    By the pieces lay a large square wooden board. The board is divided into $$$n^2$$$ cells arranged into $$$n$$$ rows and $$$n$$$ columns. Some of the cells are already occupied by single tiles stuck to it. The remaining cells are free.Alice started wondering whether she could fill the board completely using the pieces she had found. Of course, each piece has to cover exactly five distinct cells of the board, no two pieces can overlap and every piece should fit in the board entirely, without some parts laying outside the board borders. The board however was too large for Alice to do the tiling by hand. Can you help determine if it's possible to fully tile the board?",[]952"After the fourth season Sherlock and Moriary have realized the whole foolishness of the battle between them and decided to continue their competitions in peaceful game of Credit Cards.Rules of this game are simple: each player bring his favourite n-digit credit card. Then both players name the digits written on their cards one by one. If two digits are not equal, then the player, whose digit is smaller gets a flick (knock in the forehead usually made with a forefinger) from the other player. For example, if n = 3, Sherlock's card is 123 and Moriarty's card has number 321, first Sherlock names 1 and Moriarty names 3 so Sherlock gets a flick. Then they both digit 2 so no one gets a flick. Finally, Sherlock names 3, while Moriarty names 1 and gets a flick.Of course, Sherlock will play honestly naming digits one by one in the order they are given, while Moriary, as a true villain, plans to cheat. He is going to name his digits in some other order (however, he is not going to change the overall number of occurences of each digit). For example, in case above Moriarty could name 1, 2, 3 and get no flicks at all, or he can name 2, 3 and 1 to give Sherlock two flicks.Your goal is to find out the minimum possible number of flicks Moriarty will get (no one likes flicks) and the maximum possible number of flicks Sherlock can get from Moriarty. Note, that these two goals are different and the optimal result may be obtained by using different strategies.",[]953"The only difference between easy and hard versions is a number of elements in the array.You are given an array $$$a$$$ consisting of $$$n$$$ integers. The value of the $$$i$$$-th element of the array is $$$a_i$$$.You are also given a set of $$$m$$$ segments. The $$$j$$$-th segment is $$$[l_j; r_j]$$$, where $$$1 \le l_j \le r_j \le n$$$.You can choose some subset of the given set of segments and decrease values on each of the chosen segments by one (independently). For example, if the initial array $$$a = [0, 0, 0, 0, 0]$$$ and the given segments are $$$[1; 3]$$$ and $$$[2; 4]$$$ then you can choose both of them and the array will become $$$b = [-1, -2, -2, -1, 0]$$$.You have to choose some subset of the given segments (each segment can be chosen at most once) in such a way that if you apply this subset of segments to the array $$$a$$$ and obtain the array $$$b$$$ then the value $$$\max\limits_{i=1}^{n}b_i - \min\limits_{i=1}^{n}b_i$$$ will be maximum possible.Note that you can choose the empty set.If there are multiple answers, you can print any.If you are Python programmer, consider using PyPy instead of Python when you submit your code.",[]954"Mihai has just learned about the MEX concept and since he liked it so much, he decided to use it right away.Given an array $$$a$$$ of $$$n$$$ non-negative integers, Mihai wants to create a new array $$$b$$$ that is formed in the following way:While $$$a$$$ is not empty:   Choose an integer $$$k$$$ ($$$1 \leq k \leq |a|$$$).  Append the MEX of the first $$$k$$$ numbers of the array $$$a$$$ to the end of array $$$b$$$ and erase them from the array $$$a$$$, shifting the positions of the remaining numbers in $$$a$$$. But, since Mihai loves big arrays as much as the MEX concept, he wants the new array $$$b$$$ to be the lexicographically maximum. So, Mihai asks you to tell him what the maximum array $$$b$$$ that can be created by constructing the array optimally is.An array $$$x$$$ is lexicographically greater than an array $$$y$$$ if in the first position where $$$x$$$ and $$$y$$$ differ $$$x_i > y_i$$$ or if $$$|x| > |y|$$$ and $$$y$$$ is a prefix of $$$x$$$ (where $$$|x|$$$ denotes the size of the array $$$x$$$).The MEX of a set of non-negative integers is the minimal non-negative integer such that it is not in the set. For example, MEX({$$${1, 2, 3}$$$}) $$$= 0$$$ and MEX({$$${0, 1, 2, 4, 5}$$$}) $$$= 3$$$.",['math']955"Gardener Alexey teaches competitive programming to high school students. To congratulate Alexey on the Teacher's Day, the students have gifted him a collection of wooden sticks, where every stick has an integer length. Now Alexey wants to grow a tree from them.The tree looks like a polyline on the plane, consisting of all sticks. The polyline starts at the point $$$(0, 0)$$$. While constructing the polyline, Alexey will attach sticks to it one by one in arbitrary order. Each stick must be either vertical or horizontal (that is, parallel to $$$OX$$$ or $$$OY$$$ axis). It is not allowed for two consecutive sticks to be aligned simultaneously horizontally or simultaneously vertically. See the images below for clarification.Alexey wants to make a polyline in such a way that its end is as far as possible from $$$(0, 0)$$$. Please help him to grow the tree this way.Note that the polyline defining the form of the tree may have self-intersections and self-touches, but it can be proved that the optimal answer does not contain any self-intersections or self-touches.",['math']956"Levian works as an accountant in a large company. Levian knows how much the company has earned in each of the $$$n$$$ consecutive months — in the $$$i$$$-th month the company had income equal to $$$a_i$$$ (positive income means profit, negative income means loss, zero income means no change). Because of the general self-isolation, the first $$$\lceil \tfrac{n}{2} \rceil$$$ months income might have been completely unstable, but then everything stabilized and for the last $$$\lfloor \tfrac{n}{2} \rfloor$$$ months the income was the same.Levian decided to tell the directors $$$n-k+1$$$ numbers — the total income of the company for each $$$k$$$ consecutive months. In other words, for each $$$i$$$ between $$$1$$$ and $$$n-k+1$$$ he will say the value $$$a_i + a_{i+1} + \ldots + a_{i + k - 1}$$$. For example, if $$$a=[-1, 0, 1, 2, 2]$$$ and $$$k=3$$$ he will say the numbers $$$0, 3, 5$$$.Unfortunately, if at least one total income reported by Levian is not a profit (income $$$\le 0$$$), the directors will get angry and fire the failed accountant.Save Levian's career: find any such $$$k$$$, that for each $$$k$$$ months in a row the company had made a profit, or report that it is impossible.",[]957"Vasya trains to compose crossword puzzles. He can only compose crosswords of a very simplе type so far. All of them consist of exactly six words; the words can be read only from top to bottom vertically and from the left to the right horizontally. The words are arranged in the form of a rectangular ""eight"" or infinity sign, not necessarily symmetrical.The top-left corner of the crossword coincides with the top-left corner of the rectangle. The same thing is correct for the right-bottom corners. The crossword can't degrade, i.e. it always has exactly four blank areas, two of which are surrounded by letters. Look into the output for the samples for clarification.Help Vasya — compose a crossword of the described type using the given six words. It is allowed to use the words in any order.",[]958"  William is not only interested in trading but also in betting on sports matches. $$$n$$$ teams participate in each match. Each team is characterized by strength $$$a_i$$$. Each two teams $$$i < j$$$ play with each other exactly once. Team $$$i$$$ wins with probability $$$\frac{a_i}{a_i + a_j}$$$ and team $$$j$$$ wins with probability $$$\frac{a_j}{a_i + a_j}$$$.The team is called a winner if it directly or indirectly defeated all other teams. Team $$$a$$$ defeated (directly or indirectly) team $$$b$$$ if there is a sequence of teams $$$c_1$$$, $$$c_2$$$, ... $$$c_k$$$ such that $$$c_1 = a$$$, $$$c_k = b$$$ and team $$$c_i$$$ defeated team $$$c_{i + 1}$$$ for all $$$i$$$ from $$$1$$$ to $$$k - 1$$$. Note that it is possible that team $$$a$$$ defeated team $$$b$$$ and in the same time team $$$b$$$ defeated team $$$a$$$.William wants you to find the expected value of the number of winners.","['math', 'graphs', 'probabilities']"959"You are given string s. Let's call word any largest sequence of consecutive symbols without symbols ',' (comma) and ';' (semicolon). For example, there are four words in string ""aba,123;1a;0"": ""aba"", ""123"", ""1a"", ""0"". A word can be empty: for example, the string s="";;"" contains three empty words separated by ';'.You should find all words in the given string that are nonnegative INTEGER numbers without leading zeroes and build by them new string a. String a should contain all words that are numbers separating them by ',' (the order of numbers should remain the same as in the string s). By all other words you should build string b in the same way (the order of numbers should remain the same as in the string s).Here strings ""101"", ""0"" are INTEGER numbers, but ""01"" and ""1.0"" are not.For example, for the string aba,123;1a;0 the string a would be equal to ""123,0"" and string b would be equal to ""aba,1a"".",['strings']960"Polycarp doesn't like integers that are divisible by $$$3$$$ or end with the digit $$$3$$$ in their decimal representation. Integers that meet both conditions are disliked by Polycarp, too.Polycarp starts to write out the positive (greater than $$$0$$$) integers which he likes: $$$1, 2, 4, 5, 7, 8, 10, 11, 14, 16, \dots$$$. Output the $$$k$$$-th element of this sequence (the elements are numbered from $$$1$$$).",[]961"Xenia is an amateur programmer. Today on the IT lesson she learned about the Hamming distance.The Hamming distance between two strings s = s1s2... sn and t = t1t2... tn of equal length n is value . Record [si ≠ ti] is the Iverson notation and represents the following: if si ≠ ti, it is one, otherwise — zero.Now Xenia wants to calculate the Hamming distance between two long strings a and b. The first string a is the concatenation of n copies of string x, that is, . The second string b is the concatenation of m copies of string y. Help Xenia, calculate the required Hamming distance, given n, x, m, y.",['math']962"Little Petya likes arrays that consist of non-negative integers a lot. Recently his mom has presented him one such array consisting of n elements. Petya immediately decided to find there a segment of consecutive elements, such that the xor of all numbers from this segment was maximal possible. Help him with that.The xor operation is the bitwise exclusive ""OR"", that is denoted as ""xor"" in Pascal and ""^"" in C/C++/Java.",[]963"Theseus has just arrived to Crete to fight Minotaur. He found a labyrinth that has a form of a rectangular field of size n × m and consists of blocks of size 1 × 1.Each block of the labyrinth has a button that rotates all blocks 90 degrees clockwise. Each block rotates around its center and doesn't change its position in the labyrinth. Also, each block has some number of doors (possibly none). In one minute, Theseus can either push the button in order to rotate all the blocks 90 degrees clockwise or pass to the neighbouring block. Theseus can go from block A to some neighbouring block B only if block A has a door that leads to block B and block B has a door that leads to block A.Theseus found an entrance to labyrinth and is now located in block (xT, yT) — the block in the row xT and column yT. Theseus know that the Minotaur is hiding in block (xM, yM) and wants to know the minimum number of minutes required to get there.Theseus is a hero, not a programmer, so he asks you to help him.",['graphs']964You are given an array $$$a$$$ of $$$n$$$ integers. Initially there is only one copy of the given array.You can do operations of two types:  Choose any array and clone it. After that there is one more copy of the chosen array.  Swap two elements from any two copies (maybe in the same copy) on any positions. You need to find the minimal number of operations needed to obtain a copy where all elements are equal.,[]965"There are n banks in the city where Vasya lives, they are located in a circle, such that any two banks are neighbouring if their indices differ by no more than 1. Also, bank 1 and bank n are neighbours if n > 1. No bank is a neighbour of itself.Vasya has an account in each bank. Its balance may be negative, meaning Vasya owes some money to this bank.There is only one type of operations available: transfer some amount of money from any bank to account in any neighbouring bank. There are no restrictions on the size of the sum being transferred or balance requirements to perform this operation.Vasya doesn't like to deal with large numbers, so he asks you to determine the minimum number of operations required to change the balance of each bank account to zero. It's guaranteed, that this is possible to achieve, that is, the total balance of Vasya in all banks is equal to zero.",[]966"The Fair Nut is going to travel to the Tree Country, in which there are $$$n$$$ cities. Most of the land of this country is covered by forest. Furthermore, the local road system forms a tree (connected graph without cycles). Nut wants to rent a car in the city $$$u$$$ and go by a simple path to city $$$v$$$. He hasn't determined the path, so it's time to do it. Note that chosen path can consist of only one vertex.A filling station is located in every city. Because of strange law, Nut can buy only $$$w_i$$$ liters of gasoline in the $$$i$$$-th city. We can assume, that he has infinite money. Each road has a length, and as soon as Nut drives through this road, the amount of gasoline decreases by length. Of course, Nut can't choose a path, which consists of roads, where he runs out of gasoline. He can buy gasoline in every visited city, even in the first and the last.He also wants to find the maximum amount of gasoline that he can have at the end of the path. Help him: count it.",['trees']967"According to the regulations of Berland's army, a reconnaissance unit should consist of exactly two soldiers. Since these two soldiers shouldn't differ much, their heights can differ by at most d centimeters. Captain Bob has n soldiers in his detachment. Their heights are a1, a2, ..., an centimeters. Some soldiers are of the same height. Bob wants to know, how many ways exist to form a reconnaissance unit of two soldiers from his detachment.Ways (1, 2) and (2, 1) should be regarded as different.",[]968"Three sons inherited from their father a rectangular corn fiend divided into n × m squares. For each square we know how many tons of corn grows on it. The father, an old farmer did not love all three sons equally, which is why he bequeathed to divide his field into three parts containing A, B and C tons of corn.The field should be divided by two parallel lines. The lines should be parallel to one side of the field and to each other. The lines should go strictly between the squares of the field. Each resulting part of the field should consist of at least one square. Your task is to find the number of ways to divide the field as is described above, that is, to mark two lines, dividing the field in three parts so that on one of the resulting parts grew A tons of corn, B on another one and C on the remaining one.",[]969"There is a grid, consisting of $$$2$$$ rows and $$$m$$$ columns. The rows are numbered from $$$1$$$ to $$$2$$$ from top to bottom. The columns are numbered from $$$1$$$ to $$$m$$$ from left to right.The robot starts in a cell $$$(1, 1)$$$. In one second, it can perform either of two actions:   move into a cell adjacent by a side: up, right, down or left;  remain in the same cell. The robot is not allowed to move outside the grid.Initially, all cells, except for the cell $$$(1, 1)$$$, are locked. Each cell $$$(i, j)$$$ contains a value $$$a_{i,j}$$$ — the moment that this cell gets unlocked. The robot can only move into a cell $$$(i, j)$$$ if at least $$$a_{i,j}$$$ seconds have passed before the move.The robot should visit all cells without entering any cell twice or more (cell $$$(1, 1)$$$ is considered entered at the start). It can finish in any cell.What is the fastest the robot can achieve that?",[]970"You are given a tree (connected graph without cycles) consisting of $$$n$$$ vertices. The tree is unrooted — it is just a connected undirected graph without cycles.In one move, you can choose exactly $$$k$$$ leaves (leaf is such a vertex that is connected to only one another vertex) connected to the same vertex and remove them with edges incident to them. I.e. you choose such leaves $$$u_1, u_2, \dots, u_k$$$ that there are edges $$$(u_1, v)$$$, $$$(u_2, v)$$$, $$$\dots$$$, $$$(u_k, v)$$$ and remove these leaves and these edges.Your task is to find the maximum number of moves you can perform if you remove leaves optimally.You have to answer $$$t$$$ independent test cases.",['trees']971"This is the easy version of the problem. The only difference is maximum value of $$$a_i$$$.Once in Kostomuksha Divan found an array $$$a$$$ consisting of positive integers. Now he wants to reorder the elements of $$$a$$$ to maximize the value of the following function: $$$$$$\sum_{i=1}^n \operatorname{gcd}(a_1, \, a_2, \, \dots, \, a_i),$$$$$$ where $$$\operatorname{gcd}(x_1, x_2, \ldots, x_k)$$$ denotes the greatest common divisor of integers $$$x_1, x_2, \ldots, x_k$$$, and $$$\operatorname{gcd}(x) = x$$$ for any integer $$$x$$$.Reordering elements of an array means changing the order of elements in the array arbitrary, or leaving the initial order.Of course, Divan can solve this problem. However, he found it interesting, so he decided to share it with you.",['number theory']972"One very important person has a piece of paper in the form of a rectangle a × b.Also, he has n seals. Each seal leaves an impression on the paper in the form of a rectangle of the size xi × yi. Each impression must be parallel to the sides of the piece of paper (but seal can be rotated by 90 degrees).A very important person wants to choose two different seals and put them two impressions. Each of the selected seals puts exactly one impression. Impressions should not overlap (but they can touch sides), and the total area occupied by them should be the largest possible. What is the largest area that can be occupied by two seals?",[]973Let $$$f(x)$$$ be the sum of digits of a decimal number $$$x$$$.Find the smallest non-negative integer $$$x$$$ such that $$$f(x) + f(x + 1) + \dots + f(x + k) = n$$$.,[]974"Tsumugi brought $$$n$$$ delicious sweets to the Light Music Club. They are numbered from $$$1$$$ to $$$n$$$, where the $$$i$$$-th sweet has a sugar concentration described by an integer $$$a_i$$$.Yui loves sweets, but she can eat at most $$$m$$$ sweets each day for health reasons.Days are $$$1$$$-indexed (numbered $$$1, 2, 3, \ldots$$$). Eating the sweet $$$i$$$ at the $$$d$$$-th day will cause a sugar penalty of $$$(d \cdot a_i)$$$, as sweets become more sugary with time. A sweet can be eaten at most once.The total sugar penalty will be the sum of the individual penalties of each sweet eaten.Suppose that Yui chooses exactly $$$k$$$ sweets, and eats them in any order she wants. What is the minimum total sugar penalty she can get?Since Yui is an undecided girl, she wants you to answer this question for every value of $$$k$$$ between $$$1$$$ and $$$n$$$.",['math']975"You are given a matrix, consisting of $$$n$$$ rows and $$$m$$$ columns. The $$$j$$$-th cell of the $$$i$$$-th row contains an integer $$$a_{ij}$$$.First, you have to color each row of the matrix either red or blue in such a way that at least one row is colored red and at least one row is colored blue.Then, you have to choose an integer $$$k$$$ ($$$1 \le k < m$$$) and cut the colored matrix in such a way that the first $$$k$$$ columns become a separate matrix (the left matrix) and the last $$$m-k$$$ columns become a separate matrix (the right matrix).The coloring and the cut are called perfect if two properties hold:   every red cell in the left matrix contains an integer greater than every blue cell in the left matrix;  every blue cell in the right matrix contains an integer greater than every red cell in the right matrix. Find any perfect coloring and cut, or report that there are none.",[]976"Polycarp is a great fan of television.He wrote down all the TV programs he is interested in for today. His list contains n shows, i-th of them starts at moment li and ends at moment ri.Polycarp owns two TVs. He can watch two different shows simultaneously with two TVs but he can only watch one show at any given moment on a single TV. If one show ends at the same moment some other show starts then you can't watch them on a single TV.Polycarp wants to check out all n shows. Are two TVs enough to do so?",[]977"The city Valera lives in is going to hold elections to the city Parliament.The city has n districts and n - 1 bidirectional roads. We know that from any district there is a path along the roads to any other district. Let's enumerate all districts in some way by integers from 1 to n, inclusive. Furthermore, for each road the residents decided if it is the problem road or not. A problem road is a road that needs to be repaired.There are n candidates running the elections. Let's enumerate all candidates in some way by integers from 1 to n, inclusive. If the candidate number i will be elected in the city Parliament, he will perform exactly one promise — to repair all problem roads on the way from the i-th district to the district 1, where the city Parliament is located.Help Valera and determine the subset of candidates such that if all candidates from the subset will be elected to the city Parliament, all problem roads in the city will be repaired. If there are several such subsets, you should choose the subset consisting of the minimum number of candidates.","['graphs', 'trees']"978"You are given an array $$$a_1, a_2, \dots, a_n$$$, consisting of $$$n$$$ positive integers. Initially you are standing at index $$$1$$$ and have a score equal to $$$a_1$$$. You can perform two kinds of moves:   move right — go from your current index $$$x$$$ to $$$x+1$$$ and add $$$a_{x+1}$$$ to your score. This move can only be performed if $$$x<n$$$.  move left — go from your current index $$$x$$$ to $$$x-1$$$ and add $$$a_{x-1}$$$ to your score. This move can only be performed if $$$x>1$$$. Also, you can't perform two or more moves to the left in a row. You want to perform exactly $$$k$$$ moves. Also, there should be no more than $$$z$$$ moves to the left among them.What is the maximum score you can achieve?",[]979"You are given an integer $$$n$$$ and a string $$$s$$$ consisting of $$$2^n$$$ lowercase letters of the English alphabet. The characters of the string $$$s$$$ are $$$s_0s_1s_2\cdots s_{2^n-1}$$$.A string $$$t$$$ of length $$$2^n$$$ (whose characters are denoted by $$$t_0t_1t_2\cdots t_{2^n-1}$$$) is a xoration of $$$s$$$ if there exists an integer $$$j$$$ ($$$0\le j \leq 2^n-1$$$) such that, for each $$$0 \leq i \leq 2^n-1$$$, $$$t_i = s_{i \oplus j}$$$ (where $$$\oplus$$$ denotes the operation bitwise XOR).Find the lexicographically minimal xoration of $$$s$$$.A string $$$a$$$ is lexicographically smaller than a string $$$b$$$ if and only if one of the following holds:   $$$a$$$ is a prefix of $$$b$$$, but $$$a \ne b$$$;  in the first position where $$$a$$$ and $$$b$$$ differ, the string $$$a$$$ has a letter that appears earlier in the alphabet than the corresponding letter in $$$b$$$.  ",['strings']980"Given an array $$$a$$$, consisting of $$$n$$$ integers, find:$$$$$$\max\limits_{1 \le i < j \le n} LCM(a_i,a_j),$$$$$$where $$$LCM(x, y)$$$ is the smallest positive integer that is divisible by both $$$x$$$ and $$$y$$$. For example, $$$LCM(6, 8) = 24$$$, $$$LCM(4, 12) = 12$$$, $$$LCM(2, 3) = 6$$$.",['number theory']981"Little Chris is a huge fan of linear algebra. This time he has been given a homework about the unusual square of a square matrix.The dot product of two integer number vectors x and y of size n is the sum of the products of the corresponding components of the vectors. The unusual square of an n × n square matrix A is defined as the sum of n dot products. The i-th of them is the dot product of the i-th row vector and the i-th column vector in the matrix A.Fortunately for Chris, he has to work only in GF(2)! This means that all operations (addition, multiplication) are calculated modulo 2. In fact, the matrix A is binary: each element of A is either 0 or 1. For example, consider the following matrix A:  The unusual square of A is equal to (1·1 + 1·0 + 1·1) + (0·1 + 1·1 + 1·0) + (1·1 + 0·1 + 0·0) = 0 + 1 + 1 = 0.However, there is much more to the homework. Chris has to process q queries; each query can be one of the following:   given a row index i, flip all the values in the i-th row in A;  given a column index i, flip all the values in the i-th column in A;  find the unusual square of A. To flip a bit value w means to change it to 1 - w, i.e., 1 changes to 0 and 0 changes to 1.Given the initial matrix A, output the answers for each query of the third type! Can you solve Chris's homework?",['math']982"Despite his bad reputation, Captain Flint is a friendly person (at least, friendly to animals). Now Captain Flint is searching worthy sailors to join his new crew (solely for peaceful purposes). A sailor is considered as worthy if he can solve Flint's task.Recently, out of blue Captain Flint has been interested in math and even defined a new class of integers. Let's define a positive integer $$$x$$$ as nearly prime if it can be represented as $$$p \cdot q$$$, where $$$1 < p < q$$$ and $$$p$$$ and $$$q$$$ are prime numbers. For example, integers $$$6$$$ and $$$10$$$ are nearly primes (since $$$2 \cdot 3 = 6$$$ and $$$2 \cdot 5 = 10$$$), but integers $$$1$$$, $$$3$$$, $$$4$$$, $$$16$$$, $$$17$$$ or $$$44$$$ are not.Captain Flint guessed an integer $$$n$$$ and asked you: can you represent it as the sum of $$$4$$$ different positive integers where at least $$$3$$$ of them should be nearly prime.Uncle Bogdan easily solved the task and joined the crew. Can you do the same?","['math', 'number theory']"983"This is the easy version of this problem. The difference between easy and hard versions is only the constraints on $$$a_i$$$ and on $$$n$$$. You can make hacks only if both versions of the problem are solved.Burenka is the crown princess of Buryatia, and soon she will become the $$$n$$$-th queen of the country. There is an ancient tradition in Buryatia — before the coronation, the ruler must show their strength to the inhabitants. To determine the strength of the $$$n$$$-th ruler, the inhabitants of the country give them an array of $$$a$$$ of exactly $$$n$$$ numbers, after which the ruler must turn all the elements of the array into zeros in the shortest time. The ruler can do the following two-step operation any number of times:   select two indices $$$l$$$ and $$$r$$$, so that $$$1 \le l \le r \le n$$$ and a non-negative integer $$$x$$$, then  for all $$$l \leq i \leq r$$$ assign $$$a_i := a_i \oplus x$$$, where $$$\oplus$$$ denotes the bitwise XOR operation. It takes $$$\left\lceil \frac{r-l+1}{2} \right\rceil$$$ seconds to do this operation, where $$$\lceil y \rceil$$$ denotes $$$y$$$ rounded up to the nearest integer. Help Burenka calculate how much time she will need.",[]984"You are given an array $$$a_1, a_2, \ldots, a_n$$$.In one operation you can choose two elements $$$a_i$$$ and $$$a_j$$$ ($$$i \ne j$$$) and decrease each of them by one.You need to check whether it is possible to make all the elements equal to zero or not.",['math']985"You are given three integers $$$n$$$, $$$d$$$ and $$$k$$$.Your task is to construct an undirected tree on $$$n$$$ vertices with diameter $$$d$$$ and degree of each vertex at most $$$k$$$, or say that it is impossible.An undirected tree is a connected undirected graph with $$$n - 1$$$ edges.Diameter of a tree is the maximum length of a simple path (a path in which each vertex appears at most once) between all pairs of vertices of this tree.Degree of a vertex is the number of edges incident to this vertex (i.e. for a vertex $$$u$$$ it is the number of edges $$$(u, v)$$$ that belong to the tree, where $$$v$$$ is any other vertex of a tree).",['graphs']986"Do you know what tubular bells are? They are a musical instrument made up of cylindrical metal tubes. In an orchestra, tubular bells are used to mimic the ringing of bells.Mike has tubular bells, too! They consist of $$$n$$$ tubes, and each of the tubes has a length that can be expressed by a integer from $$$l$$$ to $$$r$$$ inclusive. It is clear that the lengths of all the tubes are different (it makes no sense to make the same tubes). It is also known that $$$r-l+1 = n$$$.Formally, we can say that Mike's tubular bells are described by a permutation $$$a$$$ of length $$$n$$$ that contains all numbers from $$$l$$$ to $$$r$$$ inclusive, with $$$a_i$$$ denoting the length of the $$$i$$$-th tube.You are offered an interesting task: to guess what Mike's instrument looks like. Simply, you must guess the permutation.Mike won't tell you $$$l$$$ or $$$r$$$. He will only tell you $$$n$$$, and will allow you to ask no more than $$$n + 5000$$$ queries.In each query, you name two positive integers $$$x$$$, $$$y$$$ such that $$$1 \le x, y \le n, x \neq y$$$. In response to this query, the program written by Mike will give you $$$\mathrm{lcm}(a_x, a_y)$$$, where $$$\mathrm{lcm}(c,d)$$$ denotes the least common multiple of $$$c$$$ and $$$d$$$.Solve Mike's problem!","['math', 'number theory', 'probabilities']"987"You've got array A, consisting of n integers and a positive integer k. Array A is indexed by integers from 1 to n.You need to permute the array elements so that value  became minimal possible. In particular, it is allowed not to change order of elements at all.",[]988"You are given an array consisting of $$$n$$$ integers $$$a_1$$$, $$$a_2$$$, ..., $$$a_n$$$. Initially $$$a_x = 1$$$, all other elements are equal to $$$0$$$.You have to perform $$$m$$$ operations. During the $$$i$$$-th operation, you choose two indices $$$c$$$ and $$$d$$$ such that $$$l_i \le c, d \le r_i$$$, and swap $$$a_c$$$ and $$$a_d$$$.Calculate the number of indices $$$k$$$ such that it is possible to choose the operations so that $$$a_k = 1$$$ in the end.",['math']989"Nam is playing with a string on his computer. The string consists of n lowercase English letters. It is meaningless, so Nam decided to make the string more beautiful, that is to make it be a palindrome by using 4 arrow keys: left, right, up, down.There is a cursor pointing at some symbol of the string. Suppose that cursor is at position i (1 ≤ i ≤ n, the string uses 1-based indexing) now. Left and right arrow keys are used to move cursor around the string. The string is cyclic, that means that when Nam presses left arrow key, the cursor will move to position i - 1 if i > 1 or to the end of the string (i. e. position n) otherwise. The same holds when he presses the right arrow key (if i = n, the cursor appears at the beginning of the string).When Nam presses up arrow key, the letter which the text cursor is pointing to will change to the next letter in English alphabet (assuming that alphabet is also cyclic, i. e. after 'z' follows 'a'). The same holds when he presses the down arrow key.Initially, the text cursor is at position p. Because Nam has a lot homework to do, he wants to complete this as fast as possible. Can you help him by calculating the minimum number of arrow keys presses to make the string to be a palindrome?",[]990"Nick had received an awesome array of integers $$$a=[a_1, a_2, \dots, a_n]$$$ as a gift for his $$$5$$$ birthday from his mother. He was already going to explore its various properties but after unpacking he was disappointed a lot because the product $$$a_1 \cdot a_2 \cdot \dots a_n$$$ of its elements seemed to him not large enough.He was ready to throw out the array, but his mother reassured him. She told him, that array would not be spoiled after the following operation: choose any index $$$i$$$ ($$$1 \le i \le n$$$) and do $$$a_i := -a_i - 1$$$.For example, he can change array $$$[3, -1, -4, 1]$$$ to an array $$$[-4, -1, 3, 1]$$$ after applying this operation to elements with indices $$$i=1$$$ and $$$i=3$$$. Kolya had immediately understood that sometimes it's possible to increase the product of integers of the array a lot. Now he has decided that he wants to get an array with the maximal possible product of integers using only this operation with its elements (possibly zero, one or more times, as many as he wants), it is not forbidden to do this operation several times for the same index. Help Kolya and print the array with the maximal possible product of elements $$$a_1 \cdot a_2 \cdot \dots a_n$$$ which can be received using only this operation in some order.If there are multiple answers, print any of them.",[]991"This is the hard version of the problem. The only difference is maximum value of $$$a_i$$$.Once in Kostomuksha Divan found an array $$$a$$$ consisting of positive integers. Now he wants to reorder the elements of $$$a$$$ to maximize the value of the following function: $$$$$$\sum_{i=1}^n \operatorname{gcd}(a_1, \, a_2, \, \dots, \, a_i),$$$$$$ where $$$\operatorname{gcd}(x_1, x_2, \ldots, x_k)$$$ denotes the greatest common divisor of integers $$$x_1, x_2, \ldots, x_k$$$, and $$$\operatorname{gcd}(x) = x$$$ for any integer $$$x$$$.Reordering elements of an array means changing the order of elements in the array arbitrary, or leaving the initial order.Of course, Divan can solve this problem. However, he found it interesting, so he decided to share it with you.",['number theory']992"Petya is a math teacher. $$$n$$$ of his students has written a test consisting of $$$m$$$ questions. For each student, it is known which questions he has answered correctly and which he has not.If the student answers the $$$j$$$-th question correctly, he gets $$$p_j$$$ points (otherwise, he gets $$$0$$$ points). Moreover, the points for the questions are distributed in such a way that the array $$$p$$$ is a permutation of numbers from $$$1$$$ to $$$m$$$.For the $$$i$$$-th student, Petya knows that he expects to get $$$x_i$$$ points for the test. Petya wonders how unexpected the results could be. Petya believes that the surprise value of the results for students is equal to $$$\sum\limits_{i=1}^{n} |x_i - r_i|$$$, where $$$r_i$$$ is the number of points that the $$$i$$$-th student has got for the test.Your task is to help Petya find such a permutation $$$p$$$ for which the surprise value of the results is maximum possible. If there are multiple answers, print any of them.",[]993You are given an undirected tree consisting of $$$n$$$ vertices. An undirected tree is a connected undirected graph with $$$n - 1$$$ edges.Your task is to add the minimum number of edges in such a way that the length of the shortest path from the vertex $$$1$$$ to any other vertex is at most $$$2$$$. Note that you are not allowed to add loops and multiple edges.,['graphs']994"This is the hard version of this problem. The only difference is the limit of $$$n$$$ - the length of the input string. In this version, $$$1 \leq n \leq 10^6$$$.Let's define a correct bracket sequence and its depth as follow:  An empty string is a correct bracket sequence with depth $$$0$$$.  If ""s"" is a correct bracket sequence with depth $$$d$$$ then ""(s)"" is a correct bracket sequence with depth $$$d + 1$$$.  If ""s"" and ""t"" are both correct bracket sequences then their concatenation ""st"" is a correct bracket sequence with depth equal to the maximum depth of $$$s$$$ and $$$t$$$. For a (not necessarily correct) bracket sequence $$$s$$$, we define its depth as the maximum depth of any correct bracket sequence induced by removing some characters from $$$s$$$ (possibly zero). For example: the bracket sequence $$$s = $$$""())(())"" has depth $$$2$$$, because by removing the third character we obtain a correct bracket sequence ""()(())"" with depth $$$2$$$.Given a string $$$a$$$ consists of only characters '(', ')' and '?'. Consider all (not necessarily correct) bracket sequences obtained by replacing all characters '?' in $$$a$$$ by either '(' or ')'. Calculate the sum of all the depths of all these bracket sequences. As this number can be large, find it modulo $$$998244353$$$.Hacks in this problem can be done only if easy and hard versions of this problem was solved.",['probabilities']995"You are given integer $$$n$$$. You have to arrange numbers from $$$1$$$ to $$$2n$$$, using each of them exactly once, on the circle, so that the following condition would be satisfied:For every $$$n$$$ consecutive numbers on the circle write their sum on the blackboard. Then any two of written on the blackboard $$$2n$$$ numbers differ not more than by $$$1$$$.For example, choose $$$n = 3$$$. On the left you can see an example of a valid arrangement: $$$1 + 4 + 5 = 10$$$, $$$4 + 5 + 2 = 11$$$, $$$5 + 2 + 3 = 10$$$, $$$2 + 3 + 6 = 11$$$, $$$3 + 6 + 1 = 10$$$, $$$6 + 1 + 4 = 11$$$, any two numbers differ by at most $$$1$$$. On the right you can see an invalid arrangement: for example, $$$5 + 1 + 6 = 12$$$, and $$$3 + 2 + 4 = 9$$$, $$$9$$$ and $$$12$$$ differ more than by $$$1$$$.  ",['math']996"Ray lost his array and needs to find it by asking Omkar. Omkar is willing to disclose that the array has the following qualities:  The array has $$$n$$$ ($$$1 \le n \le 2 \cdot 10^5$$$) elements.  Every element in the array $$$a_i$$$ is an integer in the range $$$1 \le a_i \le 10^9.$$$  The array is sorted in nondecreasing order. Ray is allowed to send Omkar a series of queries. A query consists of two integers, $$$l$$$ and $$$r$$$ such that $$$1 \le l \le r \le n$$$. Omkar will respond with two integers, $$$x$$$ and $$$f$$$. $$$x$$$ is the mode of the subarray from index $$$l$$$ to index $$$r$$$ inclusive. The mode of an array is defined by the number that appears the most frequently. If there are multiple numbers that appear the most number of times, the smallest such number is considered to be the mode. $$$f$$$ is the amount of times that $$$x$$$ appears in the queried subarray.The array has $$$k$$$ ($$$1 \le k \le \min(25000,n)$$$) distinct elements. However, due to Ray's sins, Omkar will not tell Ray what $$$k$$$ is. Ray is allowed to send at most $$$4k$$$ queries.Help Ray find his lost array.",[]997"We had a really tough time generating tests for problem D. In order to prepare strong tests, we had to solve the following problem.Given an undirected labeled tree consisting of $$$n$$$ vertices, find a set of segments such that:  both endpoints of each segment are integers from $$$1$$$ to $$$2n$$$, and each integer from $$$1$$$ to $$$2n$$$ should appear as an endpoint of exactly one segment;  all segments are non-degenerate;  for each pair $$$(i, j)$$$ such that $$$i \ne j$$$, $$$i \in [1, n]$$$ and $$$j \in [1, n]$$$, the vertices $$$i$$$ and $$$j$$$ are connected with an edge if and only if the segments $$$i$$$ and $$$j$$$ intersect, but neither segment $$$i$$$ is fully contained in segment $$$j$$$, nor segment $$$j$$$ is fully contained in segment $$$i$$$. Can you solve this problem too?",['trees']998"A string t is called an anagram of the string s, if it is possible to rearrange letters in t so that it is identical to the string s. For example, the string ""aab"" is an anagram of the string ""aba"" and the string ""aaa"" is not.The string t is called a substring of the string s if it can be read starting from some position in the string s. For example, the string ""aba"" has six substrings: ""a"", ""b"", ""a"", ""ab"", ""ba"", ""aba"".You are given a string s, consisting of lowercase Latin letters and characters ""?"". You are also given a string p, consisting of lowercase Latin letters only. Let's assume that a string is good if you can obtain an anagram of the string p from it, replacing the ""?"" characters by Latin letters. Each ""?"" can be replaced by exactly one character of the Latin alphabet. For example, if the string p = «aba», then the string ""a??"" is good, and the string «?bc» is not. Your task is to find the number of good substrings of the string s (identical substrings must be counted in the answer several times).",['strings']999"You are given an array a of size n, and q queries to it. There are queries of two types:   1 li ri — perform a cyclic shift of the segment [li, ri] to the right. That is, for every x such that li ≤ x < ri new value of ax + 1 becomes equal to old value of ax, and new value of ali becomes equal to old value of ari;  2 li ri — reverse the segment [li, ri].  There are m important indices in the array b1, b2, ..., bm. For each i such that 1 ≤ i ≤ m you have to output the number that will have index bi in the array after all queries are performed.",[]1000"Instructors of Some Informatics School make students go to bed.The house contains n rooms, in each room exactly b students were supposed to sleep. However, at the time of curfew it happened that many students are not located in their assigned rooms. The rooms are arranged in a row and numbered from 1 to n. Initially, in i-th room there are ai students. All students are currently somewhere in the house, therefore a1 + a2 + ... + an = nb. Also 2 instructors live in this house.The process of curfew enforcement is the following. One instructor starts near room 1 and moves toward room n, while the second instructor starts near room n and moves toward room 1. After processing current room, each instructor moves on to the next one. Both instructors enter rooms and move simultaneously, if n is odd, then only the first instructor processes the middle room. When all rooms are processed, the process ends.When an instructor processes a room, she counts the number of students in the room, then turns off the light, and locks the room. Also, if the number of students inside the processed room is not equal to b, the instructor writes down the number of this room into her notebook (and turns off the light, and locks the room). Instructors are in a hurry (to prepare the study plan for the next day), so they don't care about who is in the room, but only about the number of students.While instructors are inside the rooms, students can run between rooms that are not locked and not being processed. A student can run by at most d rooms, that is she can move to a room with number that differs my at most d. Also, after (or instead of) running each student can hide under a bed in a room she is in. In this case the instructor will not count her during the processing. In each room any number of students can hide simultaneously.Formally, here is what's happening:  A curfew is announced, at this point in room i there are ai students.  Each student can run to another room but not further than d rooms away from her initial room, or stay in place. After that each student can optionally hide under a bed.  Instructors enter room 1 and room n, they count students there and lock the room (after it no one can enter or leave this room).  Each student from rooms with numbers from 2 to n - 1 can run to another room but not further than d rooms away from her current room, or stay in place. Each student can optionally hide under a bed.  Instructors move from room 1 to room 2 and from room n to room n - 1.  This process continues until all rooms are processed. Let x1 denote the number of rooms in which the first instructor counted the number of non-hidden students different from b, and x2 be the same number for the second instructor. Students know that the principal will only listen to one complaint, therefore they want to minimize the maximum of numbers xi. Help them find this value if they use the optimal strategy.",[]1001"Given a cyclic array $$$a$$$ of size $$$n$$$, where $$$a_i$$$ is the value of $$$a$$$ in the $$$i$$$-th position, there may be repeated values. Let us define that a permutation of $$$a$$$ is equal to another permutation of $$$a$$$ if and only if their values are the same for each position $$$i$$$ or we can transform them to each other by performing some cyclic rotation. Let us define for a cyclic array $$$b$$$ its number of components as the number of connected components in a graph, where the vertices are the positions of $$$b$$$ and we add an edge between each pair of adjacent positions of $$$b$$$ with equal values (note that in a cyclic array the first and last position are also adjacents).Find the expected value of components of a permutation of $$$a$$$ if we select it equiprobably over the set of all the different permutations of $$$a$$$.","['math', 'number theory', 'probabilities']"1002"We often have to copy large volumes of information. Such operation can take up many computer resources. Therefore, in this problem you are advised to come up with a way to copy some part of a number array into another one, quickly.More formally, you've got two arrays of integers a1, a2, ..., an and b1, b2, ..., bn of length n. Also, you've got m queries of two types:  Copy the subsegment of array a of length k, starting from position x, into array b, starting from position y, that is, execute by + q = ax + q for all integer q (0 ≤ q < k). The given operation is correct — both subsegments do not touch unexistent elements.  Determine the value in position x of array b, that is, find value bx. For each query of the second type print the result — the value of the corresponding element of array b.",[]1003Berland crossword is a puzzle that is solved on a square grid with $$$n$$$ rows and $$$n$$$ columns. Initially all the cells are white.To solve the puzzle one has to color some cells on the border of the grid black in such a way that:   exactly $$$U$$$ cells in the top row are black;  exactly $$$R$$$ cells in the rightmost column are black;  exactly $$$D$$$ cells in the bottom row are black;  exactly $$$L$$$ cells in the leftmost column are black. Note that you can color zero cells black and leave every cell white.Your task is to check if there exists a solution to the given puzzle.,[]1004"One day Vasya decided to have a look at the results of Berland 1910 Football Championship’s finals. Unfortunately he didn't find the overall score of the match; however, he got hold of a profound description of the match's process. On the whole there are n lines in that description each of which described one goal. Every goal was marked with the name of the team that had scored it. Help Vasya, learn the name of the team that won the finals. It is guaranteed that the match did not end in a tie.",['strings']1005"You are given a tree of $$$n$$$ vertices numbered from $$$1$$$ to $$$n$$$. A tree is a connected undirected graph without cycles. For each $$$i=1,2, \ldots, n$$$, let $$$w_i$$$ be the weight of the $$$i$$$-th vertex. A vertex is called good if its weight is equal to the sum of the weights of all its neighbors.Initially, the weights of all nodes are unassigned. Assign positive integer weights to each vertex of the tree, such that the number of good vertices in the tree is maximized. If there are multiple ways to do it, you have to find one that minimizes the sum of weights of all vertices in the tree.",['trees']1006"You are given a permutation $$$p_1, p_2, \ldots, p_n$$$.In one move you can swap two adjacent values.You want to perform a minimum number of moves, such that in the end there will exist a subsegment $$$1,2,\ldots, k$$$, in other words in the end there should be an integer $$$i$$$, $$$1 \leq i \leq n-k+1$$$ such that $$$p_i = 1, p_{i+1} = 2, \ldots, p_{i+k-1}=k$$$.Let $$$f(k)$$$ be the minimum number of moves that you need to make a subsegment with values $$$1,2,\ldots,k$$$ appear in the permutation.You need to find $$$f(1), f(2), \ldots, f(n)$$$.",[]1007"Egor is a famous Russian singer, rapper, actor and blogger, and finally he decided to give a concert in the sunny Republic of Dagestan.There are $$$n$$$ cities in the republic, some of them are connected by $$$m$$$ directed roads without any additional conditions. In other words, road system of Dagestan represents an arbitrary directed graph. Egor will arrive to the city $$$1$$$, travel to the city $$$n$$$ by roads along some path, give a concert and fly away.As any famous artist, Egor has lots of haters and too annoying fans, so he can travel only by safe roads. There are two types of the roads in Dagestan, black and white: black roads are safe at night only, and white roads — in the morning. Before the trip Egor's manager's going to make a schedule: for each city he'll specify it's color, black or white, and then if during the trip they visit some city, the only time they can leave it is determined by the city's color: night, if it's black, and morning, if it's white. After creating the schedule Egor chooses an available path from $$$1$$$ to $$$n$$$, and for security reasons it has to be the shortest possible.Egor's manager likes Dagestan very much and wants to stay here as long as possible, so he asks you to make such schedule that there would be no path from $$$1$$$ to $$$n$$$ or the shortest path's length would be greatest possible.A path is one city or a sequence of roads such that for every road (excluding the first one) the city this road goes from is equal to the city previous road goes into. Egor can move only along paths consisting of safe roads only. The path length is equal to the number of roads in it. The shortest path in a graph is a path with smallest length.",['graphs']1008"Everybody knows that the Berland citizens are keen on health, especially students. Berland students are so tough that all they drink is orange juice!Yesterday one student, Vasya and his mates made some barbecue and they drank this healthy drink only. After they ran out of the first barrel of juice, they decided to play a simple game. All n people who came to the barbecue sat in a circle (thus each person received a unique index bi from 0 to n - 1). The person number 0 started the game (this time it was Vasya). All turns in the game were numbered by integers starting from 1. If the j-th turn was made by the person with index bi, then this person acted like that:  he pointed at the person with index (bi + 1) mod n either with an elbow or with a nod (x mod y is the remainder after dividing x by y);  if j ≥ 4 and the players who had turns number j - 1, j - 2, j - 3, made during their turns the same moves as player bi on the current turn, then he had drunk a glass of juice;  the turn went to person number (bi + 1) mod n. The person who was pointed on the last turn did not make any actions.The problem was, Vasya's drunk too much juice and can't remember the goal of the game. However, Vasya's got the recorded sequence of all the participants' actions (including himself). Now Vasya wants to find out the maximum amount of juice he could drink if he played optimally well (the other players' actions do not change). Help him.You can assume that in any scenario, there is enough juice for everybody.",[]1009"We guessed some integer number $$$x$$$. You are given a list of almost all its divisors. Almost all means that there are all divisors except $$$1$$$ and $$$x$$$ in the list.Your task is to find the minimum possible integer $$$x$$$ that can be the guessed number, or say that the input data is contradictory and it is impossible to find such number.You have to answer $$$t$$$ independent queries.","['math', 'number theory']"1010"One day Vasya came up to the blackboard and wrote out n distinct integers from 1 to n in some order in a circle. Then he drew arcs to join the pairs of integers (a, b) (a ≠ b), that are either each other's immediate neighbors in the circle, or there is number c, such that a and с are immediate neighbors, and b and c are immediate neighbors. As you can easily deduce, in the end Vasya drew 2·n arcs.For example, if the numbers are written in the circle in the order 1, 2, 3, 4, 5 (in the clockwise direction), then the arcs will join pairs of integers (1, 2), (2, 3), (3, 4), (4, 5), (5, 1), (1, 3), (2, 4), (3, 5), (4, 1) and (5, 2).Much time has passed ever since, the numbers we wiped off the blackboard long ago, but recently Vasya has found a piece of paper with 2·n written pairs of integers that were joined with the arcs on the board. Vasya asks you to find the order of numbers in the circle by these pairs.",[]1011"As we communicate, we learn much new information. However, the process of communication takes too much time. It becomes clear if we look at the words we use in our everyday speech.We can list many simple words consisting of many letters: ""information"", ""technologies"", ""university"", ""construction"", ""conservatoire"", ""refrigerator"", ""stopwatch"", ""windowsill"", ""electricity"", ""government"" and so on. Of course, we can continue listing those words ad infinitum. Fortunately, the solution for that problem has been found. To make our speech clear and brief, we should replace the initial words with those that resemble them but are much shorter. This idea hasn't been brought into life yet, that's why you are chosen to improve the situation. Let's consider the following formal model of transforming words: we shall assume that one can use n words in a chat. For each words we shall introduce a notion of its shorter variant. We shall define shorter variant of an arbitrary word s as such word t, that meets the following conditions:  it occurs in s as a subsequence,  its length ranges from one to four characters. In other words, the word t consists at least of one and at most of four characters that occur in the same order in the word s. Note that those characters do not necessarily follow in s immediately one after another. You are allowed not to shorten the initial word if its length does not exceed four characters.You are given a list of n different words. Your task is to find a set of their shortened variants. The shortened variants of all words from the list should be different.",[]1012"Timur's grandfather gifted him a chessboard to practice his chess skills. This chessboard is a grid $$$a$$$ with $$$n$$$ rows and $$$m$$$ columns with each cell having a non-negative integer written on it. Timur's challenge is to place a bishop on the board such that the sum of all cells attacked by the bishop is maximal. The bishop attacks in all directions diagonally, and there is no limit to the distance which the bishop can attack. Note that the cell on which the bishop is placed is also considered attacked. Help him find the maximal sum he can get.",[]1013"It's that time of the year, Felicity is around the corner and you can see people celebrating all around the Himalayan region. The Himalayan region has n gyms. The i-th gym has gi Pokemon in it. There are m distinct Pokemon types in the Himalayan region numbered from 1 to m. There is a special evolution camp set up in the fest which claims to evolve any Pokemon. The type of a Pokemon could change after evolving, subject to the constraint that if two Pokemon have the same type before evolving, they will have the same type after evolving. Also, if two Pokemon have different types before evolving, they will have different types after evolving. It is also possible that a Pokemon has the same type before and after evolving. Formally, an evolution plan is a permutation f of {1, 2, ..., m}, such that f(x) = y means that a Pokemon of type x evolves into a Pokemon of type y.The gym leaders are intrigued by the special evolution camp and all of them plan to evolve their Pokemons. The protocol of the mountain states that in each gym, for every type of Pokemon, the number of Pokemon of that type before evolving any Pokemon should be equal the number of Pokemon of that type after evolving all the Pokemons according to the evolution plan. They now want to find out how many distinct evolution plans exist which satisfy the protocol.Two evolution plans f1 and f2 are distinct, if they have at least one Pokemon type evolving into a different Pokemon type in the two plans, i. e. there exists an i such that f1(i) ≠ f2(i).Your task is to find how many distinct evolution plans are possible such that if all Pokemon in all the gyms are evolved, the number of Pokemon of each type in each of the gyms remains the same. As the answer can be large, output it modulo 109 + 7.",['strings']1014"AquaMoon had $$$n$$$ strings of length $$$m$$$ each. $$$n$$$ is an odd number.When AquaMoon was gone, Cirno tried to pair these $$$n$$$ strings together. After making $$$\frac{n-1}{2}$$$ pairs, she found out that there was exactly one string without the pair!In her rage, she disrupted each pair of strings. For each pair, she selected some positions (at least $$$1$$$ and at most $$$m$$$) and swapped the letters in the two strings of this pair at the selected positions.For example, if $$$m = 6$$$ and two strings ""abcdef"" and ""xyzklm"" are in one pair and Cirno selected positions $$$2$$$, $$$3$$$ and $$$6$$$ she will swap 'b' with 'y', 'c' with 'z' and 'f' with 'm'. The resulting strings will be ""ayzdem"" and ""xbcklf"".Cirno then stole away the string without pair and shuffled all remaining strings in arbitrary order.AquaMoon found the remaining $$$n-1$$$ strings in complete disarray. Also, she remembers the initial $$$n$$$ strings. She wants to know which string was stolen, but she is not good at programming. Can you help her?",['math']1015"This morning Tolik has understood that while he was sleeping he had invented an incredible problem which will be a perfect fit for Codeforces! But, as a ""Discuss tasks"" project hasn't been born yet (in English, well), he decides to test a problem and asks his uncle.After a long time thinking, Tolik's uncle hasn't any ideas on how to solve it. But, he doesn't want to tell Tolik about his inability to solve it, so he hasn't found anything better than asking you how to solve this task.In this task you are given a cell field $$$n \cdot m$$$, consisting of $$$n$$$ rows and $$$m$$$ columns, where point's coordinates $$$(x, y)$$$ mean it is situated in the $$$x$$$-th row and $$$y$$$-th column, considering numeration from one ($$$1 \leq x \leq n, 1 \leq y \leq m$$$). Initially, you stand in the cell $$$(1, 1)$$$. Every move you can jump from cell $$$(x, y)$$$, which you stand in, by any non-zero vector $$$(dx, dy)$$$, thus you will stand in the $$$(x+dx, y+dy)$$$ cell. Obviously, you can't leave the field, but also there is one more important condition — you're not allowed to use one vector twice. Your task is to visit each cell of the field exactly once (the initial cell is considered as already visited).Tolik's uncle is a very respectful person. Help him to solve this task!",[]1016"You are playing a game called Slime Escape. The game takes place on a number line. Initially, there are $$$n$$$ slimes. For all positive integers $$$i$$$ where $$$1 \le i \le n$$$, the $$$i$$$-th slime is located at position $$$i$$$ and has health $$$a_i$$$. You are controlling the slime at position $$$k$$$. There are two escapes located at positions $$$0$$$ and $$$n+1$$$. Your goal is to reach any one of the two escapes by performing any number of game moves.In one game move, you move your slime to the left or right by one position. However, if there is another slime in the new position, you must absorb it. When absorbing a slime, the health of your slime would be increased by the health of the absorbed slime, then the absorbed slime would be removed from the game.Note that some slimes might have negative health, so your health would decrease when absorbing such slimes. You lose the game immediately if your slime has negative health at any moment during the game.Can you reach one of two escapes by performing any number of game moves, without ever losing the game?",[]1017"There is a bookshelf which can fit $$$n$$$ books. The $$$i$$$-th position of bookshelf is $$$a_i = 1$$$ if there is a book on this position and $$$a_i = 0$$$ otherwise. It is guaranteed that there is at least one book on the bookshelf.In one move, you can choose some contiguous segment $$$[l; r]$$$ consisting of books (i.e. for each $$$i$$$ from $$$l$$$ to $$$r$$$ the condition $$$a_i = 1$$$ holds) and:  Shift it to the right by $$$1$$$: move the book at index $$$i$$$ to $$$i + 1$$$ for all $$$l \le i \le r$$$. This move can be done only if $$$r+1 \le n$$$ and there is no book at the position $$$r+1$$$.  Shift it to the left by $$$1$$$: move the book at index $$$i$$$ to $$$i-1$$$ for all $$$l \le i \le r$$$. This move can be done only if $$$l-1 \ge 1$$$ and there is no book at the position $$$l-1$$$. Your task is to find the minimum number of moves required to collect all the books on the shelf as a contiguous (consecutive) segment (i.e. the segment without any gaps).For example, for $$$a = [0, 0, 1, 0, 1]$$$ there is a gap between books ($$$a_4 = 0$$$ when $$$a_3 = 1$$$ and $$$a_5 = 1$$$), for $$$a = [1, 1, 0]$$$ there are no gaps between books and for $$$a = [0, 0,0]$$$ there are also no gaps between books.You have to answer $$$t$$$ independent test cases.",[]1018"Little X has met the following problem recently. Let's define f(x) as the sum of digits in decimal representation of number x (for example, f(1234) = 1 + 2 + 3 + 4). You are to calculate Of course Little X has solved this problem quickly, has locked it, and then has tried to hack others. He has seen the following C++ code:     ans = solve(l, r) % a;    if (ans <= 0)      ans += a; This code will fail only on the test with . You are given number a, help Little X to find a proper test for hack.",['math']1019"You are given a multiset $$$S$$$ initially consisting of $$$n$$$ distinct non-negative integers. A multiset is a set, that can contain some elements multiple times.You will perform the following operation $$$k$$$ times:   Add the element $$$\lceil\frac{a+b}{2}\rceil$$$ (rounded up) into $$$S$$$, where $$$a = \operatorname{mex}(S)$$$ and $$$b = \max(S)$$$. If this number is already in the set, it is added again. Here $$$\operatorname{max}$$$ of a multiset denotes the maximum integer in the multiset, and $$$\operatorname{mex}$$$ of a multiset denotes the smallest non-negative integer that is not present in the multiset. For example:    $$$\operatorname{mex}(\{1,4,0,2\})=3$$$;   $$$\operatorname{mex}(\{2,5,1\})=0$$$. Your task is to calculate the number of distinct elements in $$$S$$$ after $$$k$$$ operations will be done.",['math']1020"Peter decided to lay a parquet in the room of size n × m, the parquet consists of tiles of size 1 × 2. When the workers laid the parquet, it became clear that the tiles pattern looks not like Peter likes, and workers will have to re-lay it.The workers decided that removing entire parquet and then laying it again is very difficult task, so they decided to make such an operation every hour: remove two tiles, which form a 2 × 2 square, rotate them 90 degrees and put them back on the same place.  They have no idea how to obtain the desired configuration using these operations, and whether it is possible at all.Help Peter to make a plan for the workers or tell that it is impossible. The plan should contain at most 100 000 commands.",[]1021"There are $$$n$$$ railway stations in Berland. They are connected to each other by $$$n-1$$$ railway sections. The railway network is connected, i.e. can be represented as an undirected tree.You have a map of that network, so for each railway section you know which stations it connects.Each of the $$$n-1$$$ sections has some integer value of the scenery beauty. However, these values are not marked on the map and you don't know them. All these values are from $$$1$$$ to $$$10^6$$$ inclusive.You asked $$$m$$$ passengers some questions: the $$$j$$$-th one told you three values:  his departure station $$$a_j$$$;  his arrival station $$$b_j$$$;  minimum scenery beauty along the path from $$$a_j$$$ to $$$b_j$$$ (the train is moving along the shortest path from $$$a_j$$$ to $$$b_j$$$). You are planning to update the map and set some value $$$f_i$$$ on each railway section — the scenery beauty. The passengers' answers should be consistent with these values.Print any valid set of values $$$f_1, f_2, \dots, f_{n-1}$$$, which the passengers' answer is consistent with or report that it doesn't exist.",['trees']1022"Nezzar loves the game osu!.osu! is played on beatmaps, which can be seen as an array consisting of distinct points on a plane. A beatmap is called nice if for any three consecutive points $$$A,B,C$$$ listed in order, the angle between these three points, centered at $$$B$$$, is strictly less than $$$90$$$ degrees.  Points $$$A,B,C$$$ on the left have angle less than $$$90$$$ degrees, so they can be three consecutive points of a nice beatmap; Points $$$A',B',C'$$$ on the right have angle greater or equal to $$$90$$$ degrees, so they cannot be three consecutive points of a nice beatmap. Now Nezzar has a beatmap of $$$n$$$ distinct points $$$A_1,A_2,\ldots,A_n$$$. Nezzar would like to reorder these $$$n$$$ points so that the resulting beatmap is nice.Formally, you are required to find a permutation $$$p_1,p_2,\ldots,p_n$$$ of integers from $$$1$$$ to $$$n$$$, such that beatmap $$$A_{p_1},A_{p_2},\ldots,A_{p_n}$$$ is nice. If it is impossible, you should determine it.",['geometry']1023"You are given an array $$$a$$$ of length $$$2n$$$. Consider a partition of array $$$a$$$ into two subsequences $$$p$$$ and $$$q$$$ of length $$$n$$$ each (each element of array $$$a$$$ should be in exactly one subsequence: either in $$$p$$$ or in $$$q$$$).Let's sort $$$p$$$ in non-decreasing order, and $$$q$$$ in non-increasing order, we can denote the sorted versions by $$$x$$$ and $$$y$$$, respectively. Then the cost of a partition is defined as $$$f(p, q) = \sum_{i = 1}^n |x_i - y_i|$$$.Find the sum of $$$f(p, q)$$$ over all correct partitions of array $$$a$$$. Since the answer might be too big, print its remainder modulo $$$998244353$$$.",['math']1024"It's another Start[c]up, and that means there are T-shirts to order. In order to make sure T-shirts are shipped as soon as possible, we've decided that this year we're going to order all of the necessary T-shirts before the actual competition. The top C contestants are going to be awarded T-shirts, but we obviously don't know which contestants that will be. The plan is to get the T-Shirt sizes of all contestants before the actual competition, and then order enough T-shirts so that no matter who is in the top C we'll have T-shirts available in order to award them.In order to get the T-shirt sizes of the contestants, we will send out a survey. The survey will allow contestants to either specify a single desired T-shirt size, or two adjacent T-shirt sizes. If a contestant specifies two sizes, it means that they can be awarded either size.As you can probably tell, this plan could require ordering a lot of unnecessary T-shirts. We'd like your help to determine the minimum number of T-shirts we'll need to order to ensure that we'll be able to award T-shirts no matter the outcome of the competition.",[]1025"Given a positive integer $$$k$$$, two arrays are called $$$k$$$-similar if:  they are strictly increasing;  they have the same length;  all their elements are positive integers between $$$1$$$ and $$$k$$$ (inclusive);  they differ in exactly one position. You are given an integer $$$k$$$, a strictly increasing array $$$a$$$ and $$$q$$$ queries. For each query, you are given two integers $$$l_i \leq r_i$$$. Your task is to find how many arrays $$$b$$$ exist, such that $$$b$$$ is $$$k$$$-similar to array $$$[a_{l_i},a_{l_i+1}\ldots,a_{r_i}]$$$. ",['math']1026"You are given a directed graph consisting of n vertices and m edges (each edge is directed, so it can be traversed in only one direction). You are allowed to remove at most one edge from it.Can you make this graph acyclic by removing at most one edge from it? A directed graph is called acyclic iff it doesn't contain any cycle (a non-empty path that starts and ends in the same vertex).",['graphs']1027"At many competitions that have a word «cup» in its official name the winner is presented with an actual cup. This time the organizers of one unusual programming competition have decided to please the winner even more and to add a nameplate to the cup with the handle of the winner.The nameplate is to be rectangular and the text on it will be printed as a table of several rows and columns. Having some measurements done, the organizers have found out that the number $$$a$$$ of rows cannot be greater than $$$5$$$ while the number $$$b$$$ of columns cannot exceed $$$20$$$. Every cell of the table will contain either an asterisk («*») or a letter of user's handle.Furthermore, the organizers want the rows of the table to be uniform, which means that the number of asterisks used in different rows should differ by at most one (i.e. you can't have two asterisks in the first row and none in the second). The main goal, however, is to obtain the winner's handle precisely when reading the table from top to bottom and from left to right in every row (skipping asterisks).The organizers want for the nameplate to have as few rows as possible and among all valid tables with the minimum number of rows they want to choose the one that has the minimum number of columns.The winner is not yet determined so your task is to write a program that, given a certain handle, generates the necessary table.",[]1028"In the beginning of the new year Keivan decided to reverse his name. He doesn't like palindromes, so he changed Naviek to Navick.He is too selfish, so for a given n he wants to obtain a string of n characters, each of which is either 'a', 'b' or 'c', with no palindromes of length 3 appearing in the string as a substring. For example, the strings ""abc"" and ""abca"" suit him, while the string ""aba"" doesn't. He also want the number of letters 'c' in his string to be as little as possible.",[]1029"Define the score of some binary string $$$T$$$ as the absolute difference between the number of zeroes and ones in it. (for example, $$$T=$$$ 010001 contains $$$4$$$ zeroes and $$$2$$$ ones, so the score of $$$T$$$ is $$$|4-2| = 2$$$).Define the creepiness of some binary string $$$S$$$ as the maximum score among all of its prefixes (for example, the creepiness of $$$S=$$$ 01001 is equal to $$$2$$$ because the score of the prefix $$$S[1 \ldots 4]$$$ is $$$2$$$ and the rest of the prefixes have a score of $$$2$$$ or less).Given two integers $$$a$$$ and $$$b$$$, construct a binary string consisting of $$$a$$$ zeroes and $$$b$$$ ones with the minimum possible creepiness.",[]1030"Maxim wants to buy some games at the local game shop. There are $$$n$$$ games in the shop, the $$$i$$$-th game costs $$$c_i$$$.Maxim has a wallet which can be represented as an array of integers. His wallet contains $$$m$$$ bills, the $$$j$$$-th bill has value $$$a_j$$$.Games in the shop are ordered from left to right, Maxim tries to buy every game in that order.When Maxim stands at the position $$$i$$$ in the shop, he takes the first bill from his wallet (if his wallet is empty then he proceeds to the next position immediately) and tries to buy the $$$i$$$-th game using this bill. After Maxim tried to buy the $$$n$$$-th game, he leaves the shop.Maxim buys the $$$i$$$-th game if and only if the value of the first bill (which he takes) from his wallet is greater or equal to the cost of the $$$i$$$-th game. If he successfully buys the $$$i$$$-th game, the first bill from his wallet disappears and the next bill becomes first. Otherwise Maxim leaves the first bill in his wallet (this bill still remains the first one) and proceeds to the next game.For example, for array $$$c = [2, 4, 5, 2, 4]$$$ and array $$$a = [5, 3, 4, 6]$$$ the following process takes place: Maxim buys the first game using the first bill (its value is $$$5$$$), the bill disappears, after that the second bill (with value $$$3$$$) becomes the first one in Maxim's wallet, then Maxim doesn't buy the second game because $$$c_2 > a_2$$$, the same with the third game, then he buys the fourth game using the bill of value $$$a_2$$$ (the third bill becomes the first one in Maxim's wallet) and buys the fifth game using the bill of value $$$a_3$$$.Your task is to get the number of games Maxim will buy.",[]1031"Monocarp is playing a tower defense game. A level in the game can be represented as an OX axis, where each lattice point from $$$1$$$ to $$$n$$$ contains a tower in it.The tower in the $$$i$$$-th point has $$$c_i$$$ mana capacity and $$$r_i$$$ mana regeneration rate. In the beginning, before the $$$0$$$-th second, each tower has full mana. If, at the end of some second, the $$$i$$$-th tower has $$$x$$$ mana, then it becomes $$$\mathit{min}(x + r_i, c_i)$$$ mana for the next second.There are $$$q$$$ monsters spawning on a level. The $$$j$$$-th monster spawns at point $$$1$$$ at the beginning of $$$t_j$$$-th second, and it has $$$h_j$$$ health. Every monster is moving $$$1$$$ point per second in the direction of increasing coordinate.When a monster passes the tower, the tower deals $$$\mathit{min}(H, M)$$$ damage to it, where $$$H$$$ is the current health of the monster and $$$M$$$ is the current mana amount of the tower. This amount gets subtracted from both monster's health and tower's mana.Unfortunately, sometimes some monsters can pass all $$$n$$$ towers and remain alive. Monocarp wants to know what will be the total health of the monsters after they pass all towers.",[]1032"Whereas humans nowadays read fewer and fewer books on paper, book readership among marmots has surged. Heidi has expanded the library and is now serving longer request sequences.",[]1033"A tree is a connected undirected graph consisting of n vertices and n  -  1 edges. Vertices are numbered 1 through n.Limak is a little polar bear and Radewoosh is his evil enemy. Limak once had a tree but Radewoosh stolen it. Bear is very sad now because he doesn't remember much about the tree — he can tell you only three values n, d and h:  The tree had exactly n vertices.  The tree had diameter d. In other words, d was the biggest distance between two vertices.  Limak also remembers that he once rooted the tree in vertex 1 and after that its height was h. In other words, h was the biggest distance between vertex 1 and some other vertex. The distance between two vertices of the tree is the number of edges on the simple path between them.Help Limak to restore his tree. Check whether there exists a tree satisfying the given conditions. Find any such tree and print its edges in any order. It's also possible that Limak made a mistake and there is no suitable tree – in this case print ""-1"".","['graphs', 'trees']"1034"Polycarpus has a sequence, consisting of n non-negative integers: a1, a2, ..., an.Let's define function f(l, r) (l, r are integer, 1 ≤ l ≤ r ≤ n) for sequence a as an operation of bitwise OR of all the sequence elements with indexes from l to r. Formally: f(l, r) = al | al + 1 | ...  | ar. Polycarpus took a piece of paper and wrote out the values of function f(l, r) for all l, r (l, r are integer, 1 ≤ l ≤ r ≤ n). Now he wants to know, how many distinct values he's got in the end. Help Polycarpus, count the number of distinct values of function f(l, r) for the given sequence a.Expression x | y means applying the operation of bitwise OR to numbers x and y. This operation exists in all modern programming languages, for example, in language C++ and Java it is marked as ""|"", in Pascal — as ""or"".",[]1035"You are given a set of n points on the plane. A line containing the origin is called good, if projection of the given set to this line forms a symmetric multiset of points. Find the total number of good lines.Multiset is a set where equal elements are allowed.Multiset is called symmetric, if there is a point P on the plane such that the multiset is centrally symmetric in respect of point P.",['geometry']1036"Diana loves playing with numbers. She's got $$$n$$$ cards with positive integer numbers $$$a_i$$$ written on them. She spends her free time multiplying the numbers on the cards. She picks a non-empty subset of the cards and multiplies all the numbers $$$a_i$$$ written on them.Diana is happy when the product of the numbers ends with her favorite digit $$$d$$$. Now she is curious what cards she should pick so that the product of the numbers on them is the largest possible and the last decimal digit of the product is $$$d$$$. Please, help her.","['math', 'number theory']"1037"The difference between the versions is in the costs of operations. Solution for one version won't work for another!Alice has a grid of size $$$n \times m$$$, initially all its cells are colored white. The cell on the intersection of $$$i$$$-th row and $$$j$$$-th column is denoted as $$$(i, j)$$$. Alice can do the following operations with this grid:Choose any subrectangle containing cell $$$(1, 1)$$$, and flip the colors of all its cells. (Flipping means changing its color from white to black or from black to white). This operation costs $$$1$$$ coin.Choose any subrectangle containing cell $$$(n, 1)$$$, and flip the colors of all its cells. This operation costs $$$2$$$ coins.Choose any subrectangle containing cell $$$(1, m)$$$, and flip the colors of all its cells. This operation costs $$$4$$$ coins.Choose any subrectangle containing cell $$$(n, m)$$$, and flip the colors of all its cells. This operation costs $$$3$$$ coins. As a reminder, subrectangle is a set of all cells $$$(x, y)$$$ with $$$x_1 \le x \le x_2$$$, $$$y_1 \le y \le y_2$$$ for some $$$1 \le x_1 \le x_2 \le n$$$, $$$1 \le y_1 \le y_2 \le m$$$.Alice wants to obtain her favorite coloring with these operations. What's the smallest number of coins that she would have to spend? It can be shown that it's always possible to transform the initial grid into any other.",[]1038"The Berland Forest can be represented as an infinite cell plane. Every cell contains a tree. That is, contained before the recent events.A destructive fire raged through the Forest, and several trees were damaged by it. Precisely speaking, you have a $$$n \times m$$$ rectangle map which represents the damaged part of the Forest. The damaged trees were marked as ""X"" while the remaining ones were marked as ""."". You are sure that all burnt trees are shown on the map. All the trees outside the map are undamaged.The firemen quickly extinguished the fire, and now they are investigating the cause of it. The main version is that there was an arson: at some moment of time (let's consider it as $$$0$$$) some trees were set on fire. At the beginning of minute $$$0$$$, only the trees that were set on fire initially were burning. At the end of each minute, the fire spread from every burning tree to each of $$$8$$$ neighboring trees. At the beginning of minute $$$T$$$, the fire was extinguished.The firemen want to find the arsonists as quickly as possible. The problem is, they know neither the value of $$$T$$$ (how long the fire has been raging) nor the coordinates of the trees that were initially set on fire. They want you to find the maximum value of $$$T$$$ (to know how far could the arsonists escape) and a possible set of trees that could be initially set on fire.Note that you'd like to maximize value $$$T$$$ but the set of trees can be arbitrary.",['graphs']1039"One day, little Vasya found himself in a maze consisting of (n + 1) rooms, numbered from 1 to (n + 1). Initially, Vasya is at the first room and to get out of the maze, he needs to get to the (n + 1)-th one.The maze is organized as follows. Each room of the maze has two one-way portals. Let's consider room number i (1 ≤ i ≤ n), someone can use the first portal to move from it to room number (i + 1), also someone can use the second portal to move from it to room number pi, where 1 ≤ pi ≤ i.In order not to get lost, Vasya decided to act as follows.   Each time Vasya enters some room, he paints a cross on its ceiling. Initially, Vasya paints a cross at the ceiling of room 1.  Let's assume that Vasya is in room i and has already painted a cross on its ceiling. Then, if the ceiling now contains an odd number of crosses, Vasya uses the second portal (it leads to room pi), otherwise Vasya uses the first portal. Help Vasya determine the number of times he needs to use portals to get to room (n + 1) in the end.",[]1040"The only difference between easy and hard versions is constraints.Nauuo is a girl who loves random picture websites.One day she made a random picture website by herself which includes $$$n$$$ pictures.When Nauuo visits the website, she sees exactly one picture. The website does not display each picture with equal probability. The $$$i$$$-th picture has a non-negative weight $$$w_i$$$, and the probability of the $$$i$$$-th picture being displayed is $$$\frac{w_i}{\sum_{j=1}^nw_j}$$$. That is to say, the probability of a picture to be displayed is proportional to its weight.However, Nauuo discovered that some pictures she does not like were displayed too often. To solve this problem, she came up with a great idea: when she saw a picture she likes, she would add $$$1$$$ to its weight; otherwise, she would subtract $$$1$$$ from its weight.Nauuo will visit the website $$$m$$$ times. She wants to know the expected weight of each picture after all the $$$m$$$ visits modulo $$$998244353$$$. Can you help her?The expected weight of the $$$i$$$-th picture can be denoted by $$$\frac {q_i} {p_i}$$$ where $$$\gcd(p_i,q_i)=1$$$, you need to print an integer $$$r_i$$$ satisfying $$$0\le r_i<998244353$$$ and $$$r_i\cdot p_i\equiv q_i\pmod{998244353}$$$. It can be proved that such $$$r_i$$$ exists and is unique.",['probabilities']1041In the pet store on sale there are:  $$$a$$$ packs of dog food;  $$$b$$$ packs of cat food;  $$$c$$$ packs of universal food (such food is suitable for both dogs and cats). Polycarp has $$$x$$$ dogs and $$$y$$$ cats. Is it possible that he will be able to buy food for all his animals in the store? Each of his dogs and each of his cats should receive one pack of suitable food for it.,['math']1042"A Large Software Company develops its own social network. Analysts have found that during the holidays, major sporting events and other significant events users begin to enter the network more frequently, resulting in great load increase on the infrastructure.As part of this task, we assume that the social network is 4n processes running on the n servers. All servers are absolutely identical machines, each of which has a volume of RAM of 1 GB = 1024 MB (1). Each process takes 100 MB of RAM on the server. At the same time, the needs of maintaining the viability of the server takes about 100 more megabytes of RAM. Thus, each server may have up to 9 different processes of social network.Now each of the n servers is running exactly 4 processes. However, at the moment of peak load it is sometimes necessary to replicate the existing 4n processes by creating 8n new processes instead of the old ones. More formally, there is a set of replication rules, the i-th (1 ≤ i ≤ 4n) of which has the form of ai → (bi, ci), where ai, bi and ci (1 ≤ ai, bi, ci ≤ n) are the numbers of servers. This means that instead of an old process running on server ai, there should appear two new copies of the process running on servers bi and ci. The two new replicated processes can be on the same server (i.e., bi may be equal to ci) or even on the same server where the original process was (i.e. ai may be equal to bi or ci). During the implementation of the rule ai → (bi, ci) first the process from the server ai is destroyed, then appears a process on the server bi, then appears a process on the server ci.There is a set of 4n rules, destroying all the original 4n processes from n servers, and creating after their application 8n replicated processes, besides, on each of the n servers will be exactly 8 processes. However, the rules can only be applied consecutively, and therefore the amount of RAM of the servers imposes limitations on the procedure for the application of the rules.According to this set of rules determine the order in which you want to apply all the 4n rules so that at any given time the memory of each of the servers contained at most 9 processes (old and new together), or tell that it is impossible.",[]1043"Is it rated?Here it is. The Ultimate Question of Competitive Programming, Codeforces, and Everything. And you are here to answer it.Another Codeforces round has been conducted. No two participants have the same number of points. For each participant, from the top to the bottom of the standings, their rating before and after the round is known.It's known that if at least one participant's rating has changed, then the round was rated for sure.It's also known that if the round was rated and a participant with lower rating took a better place in the standings than a participant with higher rating, then at least one round participant's rating has changed.In this problem, you should not make any other assumptions about the rating system.Determine if the current round is rated, unrated, or it's impossible to determine whether it is rated of not.",[]1044"Parmida is a clever girl and she wants to participate in Olympiads this year. Of course she wants her partner to be clever too (although he's not)! Parmida has prepared the following test problem for Pashmak.There is a sequence a that consists of n integers a1, a2, ..., an. Let's denote f(l, r, x) the number of indices k such that: l ≤ k ≤ r and ak = x. His task is to calculate the number of pairs of indicies i, j (1 ≤ i < j ≤ n) such that f(1, i, ai) > f(j, n, aj).Help Pashmak with the test.",[]1045"After celebrating the midcourse the students of one of the faculties of the Berland State University decided to conduct a vote for the best photo. They published the photos in the social network and agreed on the rules to choose a winner: the photo which gets most likes wins. If multiple photoes get most likes, the winner is the photo that gets this number first.Help guys determine the winner photo by the records of likes.",[]1046"Bees Alice and Alesya gave beekeeper Polina famous card game ""Set"" as a Christmas present. The deck consists of cards that vary in four features across three options for each kind of feature: number of shapes, shape, shading, and color. In this game, some combinations of three cards are said to make up a set. For every feature — color, number, shape, and shading — the three cards must display that feature as either all the same, or pairwise different. The picture below shows how sets look.Polina came up with a new game called ""Hyperset"". In her game, there are $$$n$$$ cards with $$$k$$$ features, each feature has three possible values: ""S"", ""E"", or ""T"". The original ""Set"" game can be viewed as ""Hyperset"" with $$$k = 4$$$.Similarly to the original game, three cards form a set, if all features are the same for all cards or are pairwise different. The goal of the game is to compute the number of ways to choose three cards that form a set.Unfortunately, winter holidays have come to an end, and it's time for Polina to go to school. Help Polina find the number of sets among the cards lying on the table.",[]1047"Palindromic characteristics of string s with length |s| is a sequence of |s| integers, where k-th number is the total number of non-empty substrings of s which are k-palindromes.A string is 1-palindrome if and only if it reads the same backward as forward.A string is k-palindrome (k > 1) if and only if:   Its left half equals to its right half.  Its left and right halfs are non-empty (k - 1)-palindromes. The left half of string t is its prefix of length ⌊|t| / 2⌋, and right half — the suffix of the same length. ⌊|t| / 2⌋ denotes the length of string t divided by 2, rounded down.Note that each substring is counted as many times as it appears in the string. For example, in the string ""aaa"" the substring ""a"" appears 3 times.",['strings']1048"Monocarp is the coach of the Berland State University programming teams. He decided to compose a problemset for a training session for his teams.Monocarp has $$$n$$$ problems that none of his students have seen yet. The $$$i$$$-th problem has a topic $$$a_i$$$ (an integer from $$$1$$$ to $$$n$$$) and a difficulty $$$b_i$$$ (an integer from $$$1$$$ to $$$n$$$). All problems are different, that is, there are no two tasks that have the same topic and difficulty at the same time.Monocarp decided to select exactly $$$3$$$ problems from $$$n$$$ problems for the problemset. The problems should satisfy at least one of two conditions (possibly, both):  the topics of all three selected problems are different;  the difficulties of all three selected problems are different. Your task is to determine the number of ways to select three problems for the problemset.","['math', 'geometry']"1049"You may have already known that a standard ICPC team consists of exactly three members. The perfect team however has more restrictions. A student can have some specialization: coder or mathematician. She/he can have no specialization, but can't have both at the same time.So the team is considered perfect if it includes at least one coder, at least one mathematician and it consists of exactly three members.You are a coach at a very large university and you know that $$$c$$$ of your students are coders, $$$m$$$ are mathematicians and $$$x$$$ have no specialization.What is the maximum number of full perfect teams you can distribute them into? Note that some students can be left without a team and each student can be a part of no more than one team.You are also asked to answer $$$q$$$ independent queries.",['math']1050"Bessie is out grazing on the farm, which consists of $$$n$$$ fields connected by $$$m$$$ bidirectional roads. She is currently at field $$$1$$$, and will return to her home at field $$$n$$$ at the end of the day.The Cowfederation of Barns has ordered Farmer John to install one extra bidirectional road. The farm has $$$k$$$ special fields and he has decided to install the road between two different special fields. He may add the road between two special fields that already had a road directly connecting them.After the road is added, Bessie will return home on the shortest path from field $$$1$$$ to field $$$n$$$. Since Bessie needs more exercise, Farmer John must maximize the length of this shortest path. Help him!",['graphs']1051"Polycarp analyzes the prices of the new berPhone. At his disposal are the prices for $$$n$$$ last days: $$$a_1, a_2, \dots, a_n$$$, where $$$a_i$$$ is the price of berPhone on the day $$$i$$$.Polycarp considers the price on the day $$$i$$$ to be bad if later (that is, a day with a greater number) berPhone was sold at a lower price. For example, if $$$n=6$$$ and $$$a=[3, 9, 4, 6, 7, 5]$$$, then the number of days with a bad price is $$$3$$$ — these are days $$$2$$$ ($$$a_2=9$$$), $$$4$$$ ($$$a_4=6$$$) and $$$5$$$ ($$$a_5=7$$$).Print the number of days with a bad price.You have to answer $$$t$$$ independent data sets.",[]1052"The brave Knight came to the King and asked permission to marry the princess. The King knew that the Knight was brave, but he also wanted to know if he was smart enough. So he asked him to solve the following task.There is a permutation $$$p_i$$$ of numbers from 1 to $$$2n$$$. You can make two types of operations.   Swap $$$p_1$$$ and $$$p_2$$$, $$$p_3$$$ and $$$p_4$$$, ..., $$$p_{2n-1}$$$ and $$$p_{2n}$$$.  Swap $$$p_1$$$ and $$$p_{n+1}$$$, $$$p_2$$$ and $$$p_{n+2}$$$, ..., $$$p_{n}$$$ and $$$p_{2n}$$$. The task is to find the minimal number of operations required to sort the given permutation.The Knight was not that smart actually, but quite charming, so the princess asks you to help him to solve the King's task.",['graphs']1053"This is an interactive problem. Remember to flush your output while communicating with the testing program. You may use fflush(stdout) in C++, system.out.flush() in Java, stdout.flush() in Python or flush(output) in Pascal to flush the output. If you use some other programming language, consult its documentation. You may also refer to the guide on interactive problems: https://codeforces.com/blog/entry/45307.The jury guessed some array $$$a$$$ consisting of $$$6$$$ integers. There are $$$6$$$ special numbers — $$$4$$$, $$$8$$$, $$$15$$$, $$$16$$$, $$$23$$$, $$$42$$$ — and each of these numbers occurs in $$$a$$$ exactly once (so, $$$a$$$ is some permutation of these numbers).You don't know anything about their order, but you are allowed to ask up to $$$4$$$ queries. In each query, you may choose two indices $$$i$$$ and $$$j$$$ ($$$1 \le i, j \le 6$$$, $$$i$$$ and $$$j$$$ are not necessarily distinct), and you will get the value of $$$a_i \cdot a_j$$$ in return.Can you guess the array $$$a$$$?The array $$$a$$$ is fixed beforehand in each test, the interaction program doesn't try to adapt to your queries.",['math']1054"The only difference between this problem and the hard version is the maximum number of questions.This is an interactive problem.There is a hidden integer $$$1 \le x \le n$$$ which you have to find. In order to find it you can ask at most $$$\mathbf{82}$$$ questions.In each question you can choose a non-empty integer set $$$S$$$ and ask if $$$x$$$ belongs to $$$S$$$ or not, after each question, if $$$x$$$ belongs to $$$S$$$, you'll receive ""YES"", otherwise ""NO"".But the problem is that not all answers are necessarily true (some of them are joking), it's just guaranteed that for each two consecutive questions, at least one of them is answered correctly.Additionally to the questions, you can make at most $$$2$$$ guesses for the answer $$$x$$$. Each time you make a guess, if you guess $$$x$$$ correctly, you receive "":)"" and your program should terminate, otherwise you'll receive "":("".As a part of the joking, we will not fix the value of $$$x$$$ in the beginning. Instead, it can change throughout the interaction as long as all the previous responses are valid as described above.Note that your answer guesses are always answered correctly. If you ask a question before and after a guess, at least one of these two questions is answered correctly, as normal.",[]1055"A ski base is planned to be built in Walrusland. Recently, however, the project is still in the constructing phase. A large land lot was chosen for the construction. It contains n ski junctions, numbered from 1 to n. Initially the junctions aren't connected in any way.In the constructing process m bidirectional ski roads will be built. The roads are built one after another: first the road number 1 will be built, then the road number 2, and so on. The i-th road connects the junctions with numbers ai and bi.Track is the route with the following properties:  The route is closed, that is, it begins and ends in one and the same junction. The route contains at least one road.  The route doesn't go on one road more than once, however it can visit any junction any number of times. Let's consider the ski base as a non-empty set of roads that can be divided into one or more tracks so that exactly one track went along each road of the chosen set. Besides, each track can consist only of roads from the chosen set. Ski base doesn't have to be connected.Two ski bases are considered different if they consist of different road sets.After building each new road the Walrusland government wants to know the number of variants of choosing a ski base based on some subset of the already built roads. The government asks you to help them solve the given problem.",['graphs']1056"The nation of Panel holds an annual show called The Number Games, where each district in the nation will be represented by one contestant.The nation has $$$n$$$ districts numbered from $$$1$$$ to $$$n$$$, each district has exactly one path connecting it to every other district. The number of fans of a contestant from district $$$i$$$ is equal to $$$2^i$$$.This year, the president decided to reduce the costs. He wants to remove $$$k$$$ contestants from the games. However, the districts of the removed contestants will be furious and will not allow anyone to cross through their districts. The president wants to ensure that all remaining contestants are from districts that can be reached from one another. He also wishes to maximize the total number of fans of the participating contestants.Which contestants should the president remove?",['trees']1057"There is a string $$$s$$$ of length $$$3$$$, consisting of uppercase and lowercase English letters. Check if it is equal to ""YES"" (without quotes), where each letter can be in any case. For example, ""yES"", ""Yes"", ""yes"" are all allowable.",['strings']1058"On a chessboard with a width of $$$10^9$$$ and a height of $$$10^9$$$, the rows are numbered from bottom to top from $$$1$$$ to $$$10^9$$$, and the columns are numbered from left to right from $$$1$$$ to $$$10^9$$$. Therefore, for each cell of the chessboard you can assign the coordinates $$$(x,y)$$$, where $$$x$$$ is the column number and $$$y$$$ is the row number.Every day there are fights between black and white pieces on this board. Today, the black ones won, but at what price? Only the rook survived, and it was driven into the lower left corner — a cell with coordinates $$$(1,1)$$$. But it is still happy, because the victory has been won and it's time to celebrate it! In order to do this, the rook needs to go home, namely — on the upper side of the field (that is, in any cell that is in the row with number $$$10^9$$$).Everything would have been fine, but the treacherous white figures put spells on some places of the field before the end of the game. There are two types of spells:   Vertical. Each of these is defined by one number $$$x$$$. Such spells create an infinite blocking line between the columns $$$x$$$ and $$$x+1$$$.  Horizontal. Each of these is defined by three numbers $$$x_1$$$, $$$x_2$$$, $$$y$$$. Such spells create a blocking segment that passes through the top side of the cells, which are in the row $$$y$$$ and in columns from $$$x_1$$$ to $$$x_2$$$ inclusive. The peculiarity of these spells is that it is impossible for a certain pair of such spells to have a common point. Note that horizontal spells can have common points with vertical spells.    An example of a chessboard. Let's recall that the rook is a chess piece that in one move can move to any point that is in the same row or column with its initial position. In our task, the rook can move from the cell $$$(r_0,c_0)$$$ into the cell $$$(r_1,c_1)$$$ only under the condition that $$$r_1 = r_0$$$ or $$$c_1 = c_0$$$ and there is no blocking lines or blocking segments between these cells (For better understanding, look at the samples).Fortunately, the rook can remove spells, but for this it has to put tremendous efforts, therefore, it wants to remove the minimum possible number of spells in such way, that after this it can return home. Find this number!",[]1059"Sereja has two sequences a and b and number p. Sequence a consists of n integers a1, a2, ..., an. Similarly, sequence b consists of m integers b1, b2, ..., bm. As usual, Sereja studies the sequences he has. Today he wants to find the number of positions q (q + (m - 1)·p ≤ n; q ≥ 1), such that sequence b can be obtained from sequence aq, aq + p, aq + 2p, ..., aq + (m - 1)p by rearranging elements.Sereja needs to rush to the gym, so he asked to find all the described positions of q.",[]1060"Ivan is going to sleep now and wants to set his alarm clock. There will be many necessary events tomorrow, the $$$i$$$-th of them will start during the $$$x_i$$$-th minute. Ivan doesn't want to skip any of the events, so he has to set his alarm clock in such a way that it rings during minutes $$$x_1, x_2, \dots, x_n$$$, so he will be awake during each of these minutes (note that it does not matter if his alarm clock will ring during any other minute).Ivan can choose two properties for the alarm clock — the first minute it will ring (let's denote it as $$$y$$$) and the interval between two consecutive signals (let's denote it by $$$p$$$). After the clock is set, it will ring during minutes $$$y, y + p, y + 2p, y + 3p$$$ and so on.Ivan can choose any minute as the first one, but he cannot choose any arbitrary value of $$$p$$$. He has to pick it among the given values $$$p_1, p_2, \dots, p_m$$$ (his phone does not support any other options for this setting).So Ivan has to choose the first minute $$$y$$$ when the alarm clock should start ringing and the interval between two consecutive signals $$$p_j$$$ in such a way that it will ring during all given minutes $$$x_1, x_2, \dots, x_n$$$ (and it does not matter if his alarm clock will ring in any other minutes).Your task is to tell the first minute $$$y$$$ and the index $$$j$$$ such that if Ivan sets his alarm clock with properties $$$y$$$ and $$$p_j$$$ it will ring during all given minutes $$$x_1, x_2, \dots, x_n$$$ or say that it is impossible to choose such values of the given properties. If there are multiple answers, you can print any.","['math', 'number theory']"1061"There was a string $$$s$$$ which was supposed to be encrypted. For this reason, all $$$26$$$ lowercase English letters were arranged in a circle in some order, afterwards, each letter in $$$s$$$ was replaced with the one that follows in clockwise order, in that way the string $$$t$$$ was obtained. You are given a string $$$t$$$. Determine the lexicographically smallest string $$$s$$$ that could be a prototype of the given string $$$t$$$.A string $$$a$$$ is lexicographically smaller than a string $$$b$$$ of the same length if and only if:   in the first position where $$$a$$$ and $$$b$$$ differ, the string $$$a$$$ has a letter, that appears earlier in the alphabet than the corresponding letter in $$$b$$$.  ","['graphs', 'strings']"1062"There are n student groups at the university. During the study day, each group can take no more than 7 classes. Seven time slots numbered from 1 to 7 are allocated for the classes.The schedule on Monday is known for each group, i. e. time slots when group will have classes are known.Your task is to determine the minimum number of rooms needed to hold classes for all groups on Monday. Note that one room can hold at most one group class in a single time slot.",[]1063"You are at the top left cell $$$(1, 1)$$$ of an $$$n \times m$$$ labyrinth. Your goal is to get to the bottom right cell $$$(n, m)$$$. You can only move right or down, one cell per step. Moving right from a cell $$$(x, y)$$$ takes you to the cell $$$(x, y + 1)$$$, while moving down takes you to the cell $$$(x + 1, y)$$$.Some cells of the labyrinth contain rocks. When you move to a cell with rock, the rock is pushed to the next cell in the direction you're moving. If the next cell contains a rock, it gets pushed further, and so on.The labyrinth is surrounded by impenetrable walls, thus any move that would put you or any rock outside of the labyrinth is illegal.Count the number of different legal paths you can take from the start to the goal modulo $$$10^9 + 7$$$. Two paths are considered different if there is at least one cell that is visited in one path, but not visited in the other.",[]1064"A rooted tree is a non-directed connected graph without any cycles with a distinguished vertex, which is called the tree root. Consider the vertices of a rooted tree, that consists of n vertices, numbered from 1 to n. In this problem the tree root is the vertex number 1.Let's represent the length of the shortest by the number of edges path in the tree between vertices v and u as d(v, u).A parent of vertex v in the rooted tree with the root in vertex r (v ≠ r) is vertex pv, such that d(r, pv) + 1 = d(r, v) and d(pv, v) = 1. For example, on the picture the parent of vertex v = 5 is vertex p5 = 2.One day Polycarpus came across a rooted tree, consisting of n vertices. The tree wasn't exactly ordinary: it had strings written on its edges. Polycarpus positioned the tree on the plane so as to make all edges lead from top to bottom if you go from the vertex parent to the vertex (see the picture). For any edge that lead from vertex pv to vertex v (1 < v ≤ n), he knows string sv that is written on it. All strings are written on the edges from top to bottom. For example, on the picture s7=""ba"". The characters in the strings are numbered starting from 0.    An example of Polycarpus's tree (corresponds to the example from the statement) Polycarpus defines the position in this tree as a specific letter on a specific string. The position is written as a pair of integers (v, x) that means that the position is the x-th letter of the string sv (1 < v ≤ n, 0 ≤ x < |sv|), where |sv| is the length of string sv. For example, the highlighted letters are positions (2, 1) and (3, 1).Let's consider the pair of positions (v, x) and (u, y) in Polycarpus' tree, such that the way from the first position to the second goes down on each step. We will consider that the pair of such positions defines string z. String z consists of all letters on the way from (v, x) to (u, y), written in the order of this path. For example, in the picture the highlighted positions define string ""bacaba"".Polycarpus has a string t, he wants to know the number of pairs of positions that define string t. Note that the way from the first position to the second in the pair must go down everywhere. Help him with this challenging tree-string problem!",['strings']1065"You are given a binary string $$$s$$$ of length $$$n$$$.Let's define $$$d_i$$$ as the number whose decimal representation is $$$s_i s_{i+1}$$$ (possibly, with a leading zero). We define $$$f(s)$$$ to be the sum of all the valid $$$d_i$$$. In other words, $$$f(s) = \sum\limits_{i=1}^{n-1} d_i$$$.For example, for the string $$$s = 1011$$$:   $$$d_1 = 10$$$ (ten);  $$$d_2 = 01$$$ (one)  $$$d_3 = 11$$$ (eleven);  $$$f(s) = 10 + 01 + 11 = 22$$$. In one operation you can swap any two adjacent elements of the string. Find the minimum value of $$$f(s)$$$ that can be achieved if at most $$$k$$$ operations are allowed.","['math', 'strings']"1066"You are given an array $$$a[0 \dots n-1]$$$ of $$$n$$$ integers. This array is called a ""valley"" if there exists exactly one subarray $$$a[l \dots r]$$$ such that:  $$$0 \le l \le r \le n-1$$$,  $$$a_l = a_{l+1} = a_{l+2} = \dots = a_r$$$,  $$$l = 0$$$ or $$$a_{l-1} > a_{l}$$$,  $$$r = n-1$$$ or $$$a_r < a_{r+1}$$$. Here are three examples:  The first image shows the array [$$$3, 2, 2, 1, 2, 2, 3$$$], it is a valley because only subarray with indices $$$l=r=3$$$ satisfies the condition.The second image shows the array [$$$1, 1, 1, 2, 3, 3, 4, 5, 6, 6, 6$$$], it is a valley because only subarray with indices $$$l=0, r=2$$$ satisfies the codition.The third image shows the array [$$$1, 2, 3, 4, 3, 2, 1$$$], it is not a valley because two subarrays $$$l=r=0$$$ and $$$l=r=6$$$ that satisfy the condition.You are asked whether the given array is a valley or not.Note that we consider the array to be indexed from $$$0$$$.",[]1067"A new e-mail service ""Berlandesk"" is going to be opened in Berland in the near future. The site administration wants to launch their project as soon as possible, that's why they ask you to help. You're suggested to implement the prototype of site registration system. The system should work on the following principle. Each time a new user wants to register, he sends to the system a request with his name. If such a name does not exist in the system database, it is inserted into the database, and the user gets the response OK, confirming the successful registration. If the name already exists in the system database, the system makes up a new user name, sends it to the user as a prompt and also inserts the prompt into the database. The new name is formed by the following rule. Numbers, starting with 1, are appended one after another to name (name1, name2, ...), among these numbers the least i is found so that namei does not yet exist in the database.",[]1068"Madoka as a child was an extremely capricious girl, and one of her favorite pranks was drawing on her wall. According to Madoka's memories, the wall was a table of $$$n$$$ rows and $$$m$$$ columns, consisting only of zeroes and ones. The coordinate of the cell in the $$$i$$$-th row and the $$$j$$$-th column ($$$1 \le i \le n$$$, $$$1 \le j \le m$$$) is $$$(i, j)$$$.One day she saw a picture ""Mahou Shoujo Madoka Magica"" and decided to draw it on her wall. Initially, the Madoka's table is a table of size $$$n \times m$$$ filled with zeroes. Then she applies the following operation any number of times:Madoka selects any rectangular subtable of the table and paints it in a chess coloring (the upper left corner of the subtable always has the color $$$0$$$). Note that some cells may be colored several times. In this case, the final color of the cell is equal to the color obtained during the last repainting.  White color means $$$0$$$, black means $$$1$$$. So, for example, the table in the first picture is painted in a chess coloring, and the others are not. For better understanding of the statement, we recommend you to read the explanation of the first test.Help Madoka and find some sequence of no more than $$$n \cdot m$$$ operations that allows you to obtain the picture she wants, or determine that this is impossible.",[]1069"Consider a table of size $$$n \times m$$$, initially fully white. Rows are numbered $$$1$$$ through $$$n$$$ from top to bottom, columns $$$1$$$ through $$$m$$$ from left to right. Some square inside the table with odd side length was painted black. Find the center of this square.",[]1070"Your company was appointed to lay new asphalt on the highway of length $$$n$$$. You know that every day you can either repair one unit of the highway (lay new asphalt over one unit of the highway) or skip repairing.Skipping the repair is necessary because of the climate. The climate in your region is periodical: there are $$$g$$$ days when the weather is good and if you lay new asphalt these days it becomes high-quality pavement; after that, the weather during the next $$$b$$$ days is bad, and if you lay new asphalt these days it becomes low-quality pavement; again $$$g$$$ good days, $$$b$$$ bad days and so on.You can be sure that you start repairing at the start of a good season, in other words, days $$$1, 2, \dots, g$$$ are good.You don't really care about the quality of the highway, you just want to make sure that at least half of the highway will have high-quality pavement. For example, if the $$$n = 5$$$ then at least $$$3$$$ units of the highway should have high quality; if $$$n = 4$$$ then at least $$$2$$$ units should have high quality.What is the minimum number of days is needed to finish the repair of the whole highway?",['math']1071"An array is sorted if it has no inversionsA Young BoyYou are given an array of $$$n$$$ positive integers $$$a_1,a_2,\ldots,a_n$$$. In one operation you do the following:   Choose any integer $$$x$$$.  For all $$$i$$$ such that $$$a_i = x$$$, do $$$a_i := 0$$$ (assign $$$0$$$ to $$$a_i$$$). Find the minimum number of operations required to sort the array in non-decreasing order.",[]1072"Vitaly enrolled in the course Advanced Useless Algorithms. The course consists of $$$n$$$ tasks. Vitaly calculated that he has $$$a_i$$$ hours to do the task $$$i$$$ from the day he enrolled in the course. That is, the deadline before the $$$i$$$-th task is $$$a_i$$$ hours. The array $$$a$$$ is sorted in ascending order, in other words, the job numbers correspond to the order in which the assignments are turned in.Vitaly does everything conscientiously, so he wants to complete each task by $$$100$$$ percent, or more. Initially, his completion rate for each task is $$$0$$$ percent.Vitaly has $$$m$$$ training options, each option can be used not more than once. The $$$i$$$th option is characterized by three integers: $$$e_i, t_i$$$ and $$$p_i$$$. If Vitaly uses the $$$i$$$th option, then after $$$t_i$$$ hours (from the current moment) he will increase the progress of the task $$$e_i$$$ by $$$p_i$$$ percent. For example, let Vitaly have $$$3$$$ of tasks to complete. Let the array $$$a$$$ have the form: $$$a = [5, 7, 8]$$$. Suppose Vitaly has $$$5$$$ of options: $$$[e_1=1, t_1=1, p_1=30]$$$, $$$[e_2=2, t_2=3, p_2=50]$$$, $$$[e_3=2, t_3=3, p_3=100]$$$, $$$[e_4=1, t_4=1, p_4=80]$$$, $$$[e_5=3, t_5=3, p_5=100]$$$. Then, if Vitaly prepares in the following way, he will be able to complete everything in time:   Vitaly chooses the $$$4$$$-th option. Then in $$$1$$$ hour, he will complete the $$$1$$$-st task at $$$80$$$ percent. He still has $$$4$$$ hours left before the deadline for the $$$1$$$-st task.  Vitaly chooses the $$$3$$$-rd option. Then in $$$3$$$ hours, he will complete the $$$2$$$-nd task in its entirety. He has another $$$1$$$ hour left before the deadline for the $$$1$$$-st task and $$$4$$$ hours left before the deadline for the $$$3$$$-rd task.  Vitaly chooses the $$$1$$$-st option. Then after $$$1$$$ hour, he will complete the $$$1$$$-st task for $$$110$$$ percent, which means that he will complete the $$$1$$$-st task just in time for the deadline.  Vitaly chooses the $$$5$$$-th option. He will complete the $$$3$$$-rd task for $$$2$$$ hours, and after another $$$1$$$ hour, Vitaly will complete the $$$3$$$-rd task in its entirety. Thus, Vitaly has managed to complete the course completely and on time, using the $$$4$$$ options.Help Vitaly — print the options for Vitaly to complete the tasks in the correct order. Please note: each option can be used not more than once. If there are several possible answers, it is allowed to output any of them.",[]1073"The only difference between the two versions is that in this version $$$n \leq 1000$$$ and the sum of $$$n$$$ over all test cases does not exceed $$$1000$$$.A terminal is a row of $$$n$$$ equal segments numbered $$$1$$$ to $$$n$$$ in order. There are two terminals, one above the other. You are given an array $$$a$$$ of length $$$n$$$. For all $$$i = 1, 2, \dots, n$$$, there should be a straight wire from some point on segment $$$i$$$ of the top terminal to some point on segment $$$a_i$$$ of the bottom terminal. You can't select the endpoints of a segment. For example, the following pictures show two possible wirings if $$$n=7$$$ and $$$a=[4,1,4,6,7,7,5]$$$.  A crossing occurs when two wires share a point in common. In the picture above, crossings are circled in red.What is the maximum number of crossings there can be if you place the wires optimally?",[]1074"There are n schoolchildren, boys and girls, lined up in the school canteen in front of the bun stall. The buns aren't ready yet and the line is undergoing some changes.Each second all boys that stand right in front of girls, simultaneously swap places with the girls (so that the girls could go closer to the beginning of the line). In other words, if at some time the i-th position has a boy and the (i + 1)-th position has a girl, then in a second, the i-th position will have a girl and the (i + 1)-th one will have a boy.Let's take an example of a line of four people: a boy, a boy, a girl, a girl (from the beginning to the end of the line). Next second the line will look like that: a boy, a girl, a boy, a girl. Next second it will be a girl, a boy, a girl, a boy. Next second it will be a girl, a girl, a boy, a boy. The line won't change any more.Your task is: given the arrangement of the children in the line to determine the time needed to move all girls in front of boys (in the example above it takes 3 seconds). Baking buns takes a lot of time, so no one leaves the line until the line stops changing.",[]1075"Simon has an array a1, a2, ..., an, consisting of n positive integers. Today Simon asked you to find a pair of integers l, r (1 ≤ l ≤ r ≤ n), such that the following conditions hold:  there is integer j (l ≤ j ≤ r), such that all integers al, al + 1, ..., ar are divisible by aj;  value r - l takes the maximum value among all pairs for which condition 1 is true; Help Simon, find the required pair of numbers (l, r). If there are multiple required pairs find all of them.",['math']1076"Madoka is a very strange girl, and therefore she suddenly wondered how many pairs of integers $$$(a, b)$$$ exist, where $$$1 \leq a, b \leq n$$$, for which $$$\frac{\operatorname{lcm}(a, b)}{\operatorname{gcd}(a, b)} \leq 3$$$.In this problem, $$$\operatorname{gcd}(a, b)$$$ denotes the greatest common divisor of the numbers $$$a$$$ and $$$b$$$, and $$$\operatorname{lcm}(a, b)$$$ denotes the smallest common multiple of the numbers $$$a$$$ and $$$b$$$.","['math', 'number theory']"1077"You all know that the Library of Bookland is the largest library in the world. There are dozens of thousands of books in the library.Some long and uninteresting story was removed...The alphabet of Bookland is so large that its letters are denoted by positive integers. Each letter can be small or large, the large version of a letter x is denoted by x'. BSCII encoding, which is used everywhere in Bookland, is made in that way so that large letters are presented in the order of the numbers they are denoted by, and small letters are presented in the order of the numbers they are denoted by, but all large letters are before all small letters. For example, the following conditions hold: 2 < 3, 2' < 3', 3' < 2.A word x1, x2, ..., xa is not lexicographically greater than y1, y2, ..., yb if one of the two following conditions holds:   a ≤ b and x1 = y1, ..., xa = ya, i.e. the first word is the prefix of the second word;  there is a position 1 ≤ j ≤ min(a, b), such that x1 = y1, ..., xj - 1 = yj - 1 and xj < yj, i.e. at the first position where the words differ the first word has a smaller letter than the second word has.  For example, the word ""3' 7 5"" is before the word ""2 4' 6"" in lexicographical order. It is said that sequence of words is in lexicographical order if each word is not lexicographically greater than the next word in the sequence.Denis has a sequence of words consisting of small letters only. He wants to change some letters to large (let's call this process a capitalization) in such a way that the sequence of words is in lexicographical order. However, he soon realized that for some reason he can't change a single letter in a single word. He only can choose a letter and change all of its occurrences in all words to large letters. He can perform this operation any number of times with arbitrary letters of Bookland's alphabet.Help Denis to choose which letters he needs to capitalize (make large) in order to make the sequence of words lexicographically ordered, or determine that it is impossible.Note that some words can be equal.",['graphs']1078" As the boat drifts down the river, a wood full of blossoms shows up on the riverfront.""I've been here once,"" Mino exclaims with delight, ""it's breathtakingly amazing.""""What is it like?""""Look, Kanno, you've got your paintbrush, and I've got my words. Have a try, shall we?"" There are four kinds of flowers in the wood, Amaranths, Begonias, Centaureas and Dianthuses.The wood can be represented by a rectangular grid of $$$n$$$ rows and $$$m$$$ columns. In each cell of the grid, there is exactly one type of flowers.According to Mino, the numbers of connected components formed by each kind of flowers are $$$a$$$, $$$b$$$, $$$c$$$ and $$$d$$$ respectively. Two cells are considered in the same connected component if and only if a path exists between them that moves between cells sharing common edges and passes only through cells containing the same flowers.You are to help Kanno depict such a grid of flowers, with $$$n$$$ and $$$m$$$ arbitrarily chosen under the constraints given below. It can be shown that at least one solution exists under the constraints of this problem.Note that you can choose arbitrary $$$n$$$ and $$$m$$$ under the constraints below, they are not given in the input.",['graphs']1079"""Eat a beaver, save a tree!"" — That will be the motto of ecologists' urgent meeting in Beaverley Hills.And the whole point is that the population of beavers on the Earth has reached incredible sizes! Each day their number increases in several times and they don't even realize how much their unhealthy obsession with trees harms the nature and the humankind. The amount of oxygen in the atmosphere has dropped to 17 per cent and, as the best minds of the world think, that is not the end.In the middle of the 50-s of the previous century a group of soviet scientists succeed in foreseeing the situation with beavers and worked out a secret technology to clean territory. The technology bears a mysterious title ""Beavermuncher-0xFF"". Now the fate of the planet lies on the fragile shoulders of a small group of people who has dedicated their lives to science.The prototype is ready, you now need to urgently carry out its experiments in practice. You are given a tree, completely occupied by beavers. A tree is a connected undirected graph without cycles. The tree consists of n vertices, the i-th vertex contains ki beavers. ""Beavermuncher-0xFF"" works by the following principle: being at some vertex u, it can go to the vertex v, if they are connected by an edge, and eat exactly one beaver located at the vertex v. It is impossible to move to the vertex v if there are no beavers left in v. ""Beavermuncher-0xFF"" cannot just stand at some vertex and eat beavers in it. ""Beavermuncher-0xFF"" must move without stops.Why does the ""Beavermuncher-0xFF"" works like this? Because the developers have not provided place for the battery in it and eating beavers is necessary for converting their mass into pure energy.It is guaranteed that the beavers will be shocked by what is happening, which is why they will not be able to move from a vertex of the tree to another one. As for the ""Beavermuncher-0xFF"", it can move along each edge in both directions while conditions described above are fulfilled.The root of the tree is located at the vertex s. This means that the ""Beavermuncher-0xFF"" begins its mission at the vertex s and it must return there at the end of experiment, because no one is going to take it down from a high place. Determine the maximum number of beavers ""Beavermuncher-0xFF"" can eat and return to the starting vertex.",['trees']1080"Michael is accused of violating the social distancing rules and creating a risk of spreading coronavirus. He is now sent to prison. Luckily, Michael knows exactly what the prison looks like from the inside, especially since it's very simple.The prison can be represented as a rectangle $$$a\times b$$$ which is divided into $$$ab$$$ cells, each representing a prison cell, common sides being the walls between cells, and sides on the perimeter being the walls leading to freedom. Before sentencing, Michael can ask his friends among the prison employees to make (very well hidden) holes in some of the walls (including walls between cells and the outermost walls). Michael wants to be able to get out of the prison after this, no matter which cell he is placed in. However, he also wants to break as few walls as possible.Your task is to find out the smallest number of walls to be broken so that there is a path to the outside from every cell after this.",[]1081"After finding and moving to the new planet that supports human life, discussions started on which currency should be used. After long negotiations, Bitcoin was ultimately chosen as the universal currency.These were the great news for Alice, whose grandfather got into Bitcoin mining in 2013, and accumulated a lot of them throughout the years. Unfortunately, when paying something in bitcoin everyone can see how many bitcoins you have in your public address wallet. This worried Alice, so she decided to split her bitcoins among multiple different addresses, so that every address has at most $$$x$$$ satoshi (1 bitcoin = $$$10^8$$$ satoshi). She can create new public address wallets for free and is willing to pay $$$f$$$ fee in satoshi per transaction to ensure acceptable speed of transfer. The fee is deducted from the address the transaction was sent from. Tell Alice how much total fee in satoshi she will need to pay to achieve her goal.",[]1082"Professor GukiZ doesn't accept string as they are. He likes to swap some letters in string to obtain a new one.GukiZ has strings a, b, and c. He wants to obtain string k by swapping some letters in a, so that k should contain as many non-overlapping substrings equal either to b or c as possible. Substring of string x is a string formed by consecutive segment of characters from x. Two substrings of string x overlap if there is position i in string x occupied by both of them.GukiZ was disappointed because none of his students managed to solve the problem. Can you help them and find one of possible strings k?",['strings']1083"Let's call an undirected graph $$$G = (V, E)$$$ relatively prime if and only if for each edge $$$(v, u) \in E$$$  $$$GCD(v, u) = 1$$$ (the greatest common divisor of $$$v$$$ and $$$u$$$ is $$$1$$$). If there is no edge between some pair of vertices $$$v$$$ and $$$u$$$ then the value of $$$GCD(v, u)$$$ doesn't matter. The vertices are numbered from $$$1$$$ to $$$|V|$$$.Construct a relatively prime graph with $$$n$$$ vertices and $$$m$$$ edges such that it is connected and it contains neither self-loops nor multiple edges.If there exists no valid graph with the given number of vertices and edges then output ""Impossible"".If there are multiple answers then print any of them.","['math', 'graphs']"1084"Recently, Duff has been practicing weight lifting. As a hard practice, Malek gave her a task. He gave her a sequence of weights. Weight of i-th of them is 2wi pounds. In each step, Duff can lift some of the remaining weights and throw them away. She does this until there's no more weight left. Malek asked her to minimize the number of steps.  Duff is a competitive programming fan. That's why in each step, she can only lift and throw away a sequence of weights 2a1, ..., 2ak if and only if there exists a non-negative integer x such that 2a1 + 2a2 + ... + 2ak = 2x, i. e. the sum of those numbers is a power of two.Duff is a competitive programming fan, but not a programmer. That's why she asked for your help. Help her minimize the number of steps. ",[]1085"Как известно, в теплую погоду многие жители крупных городов пользуются сервисами городского велопроката. Вот и Аркадий сегодня будет добираться от школы до дома, используя городские велосипеды.Школа и дом находятся на одной прямой улице, кроме того, на той же улице есть n точек, где можно взять велосипед в прокат или сдать его. Первый велопрокат находится в точке x1 километров вдоль улицы, второй — в точке x2 и так далее, n-й велопрокат находится в точке xn. Школа Аркадия находится в точке x1 (то есть там же, где и первый велопрокат), а дом — в точке xn (то есть там же, где и n-й велопрокат). Известно, что xi < xi + 1 для всех 1 ≤ i < n.Согласно правилам пользования велопроката, Аркадий может брать велосипед в прокат только на ограниченное время, после этого он должен обязательно вернуть его в одной из точек велопроката, однако, он тут же может взять новый велосипед, и отсчет времени пойдет заново. Аркадий может брать не более одного велосипеда в прокат одновременно. Если Аркадий решает взять велосипед в какой-то точке проката, то он сдаёт тот велосипед, на котором он до него доехал, берёт ровно один новый велосипед и продолжает на нём своё движение.За отведенное время, независимо от выбранного велосипеда, Аркадий успевает проехать не больше k километров вдоль улицы. Определите, сможет ли Аркадий доехать на велосипедах от школы до дома, и если да, то какое минимальное число раз ему необходимо будет взять велосипед в прокат, включая первый велосипед? Учтите, что Аркадий не намерен сегодня ходить пешком.",[]1086"Little town Nsk consists of n junctions connected by m bidirectional roads. Each road connects two distinct junctions and no two roads connect the same pair of junctions. It is possible to get from any junction to any other junction by these roads. The distance between two junctions is equal to the minimum possible number of roads on a path between them.In order to improve the transportation system, the city council asks mayor to build one new road. The problem is that the mayor has just bought a wonderful new car and he really enjoys a ride from his home, located near junction s to work located near junction t. Thus, he wants to build a new road in such a way that the distance between these two junctions won't decrease. You are assigned a task to compute the number of pairs of junctions that are not connected by the road, such that if the new road between these two junctions is built the distance between s and t won't decrease.",['graphs']1087"Little Artem likes electronics. He can spend lots of time making different schemas and looking for novelties in the nearest electronics store. The new control element was delivered to the store recently and Artem immediately bought it.That element can store information about the matrix of integers size n × m. There are n + m inputs in that element, i.e. each row and each column can get the signal. When signal comes to the input corresponding to some row, this row cyclically shifts to the left, that is the first element of the row becomes last element, second element becomes first and so on. When signal comes to the input corresponding to some column, that column shifts cyclically to the top, that is first element of the column becomes last element, second element becomes first and so on. Rows are numbered with integers from 1 to n from top to bottom, while columns are numbered with integers from 1 to m from left to right.Artem wants to carefully study this element before using it. For that purpose he is going to set up an experiment consisting of q turns. On each turn he either sends the signal to some input or checks what number is stored at some position of the matrix.Artem has completed his experiment and has written down the results, but he has lost the chip! Help Artem find any initial matrix that will match the experiment results. It is guaranteed that experiment data is consistent, which means at least one valid matrix exists.",[]1088"Gildong is playing a video game called Block Adventure. In Block Adventure, there are $$$n$$$ columns of blocks in a row, and the columns are numbered from $$$1$$$ to $$$n$$$. All blocks have equal heights. The height of the $$$i$$$-th column is represented as $$$h_i$$$, which is the number of blocks stacked in the $$$i$$$-th column.Gildong plays the game as a character that can stand only on the top of the columns. At the beginning, the character is standing on the top of the $$$1$$$-st column. The goal of the game is to move the character to the top of the $$$n$$$-th column.The character also has a bag that can hold infinitely many blocks. When the character is on the top of the $$$i$$$-th column, Gildong can take one of the following three actions as many times as he wants:   if there is at least one block on the column, remove one block from the top of the $$$i$$$-th column and put it in the bag;  if there is at least one block in the bag, take one block out of the bag and place it on the top of the $$$i$$$-th column;  if $$$i < n$$$ and $$$|h_i - h_{i+1}| \le k$$$, move the character to the top of the $$$i+1$$$-st column. $$$k$$$ is a non-negative integer given at the beginning of the game. Note that it is only possible to move to the next column. In actions of the first two types the character remains in the $$$i$$$-th column, and the value $$$h_i$$$ changes.The character initially has $$$m$$$ blocks in the bag. Gildong wants to know if it is possible to win the game. Help Gildong find the answer to his question.",[]1089"Polycarpus takes part in the ""Field of Wonders"" TV show. The participants of the show have to guess a hidden word as fast as possible. Initially all the letters of the word are hidden.The game consists of several turns. At each turn the participant tells a letter and the TV show host responds if there is such letter in the word or not. If there is such letter then the host reveals all such letters. For example, if the hidden word is ""abacaba"" and the player tells the letter ""a"", the host will reveal letters at all positions, occupied by ""a"": 1, 3, 5 and 7 (positions are numbered from left to right starting from 1).Polycarpus knows m words of exactly the same length as the hidden word. The hidden word is also known to him and appears as one of these m words.At current moment a number of turns have already been made and some letters (possibly zero) of the hidden word are already revealed. Previously Polycarp has told exactly the letters which are currently revealed.It is Polycarpus' turn. He wants to tell a letter in such a way, that the TV show host will assuredly reveal at least one more letter. Polycarpus cannot tell the letters, which are already revealed.Your task is to help Polycarpus and find out the number of letters he can tell so that the show host will assuredly reveal at least one of the remaining letters.",['strings']1090"Little Petya very much likes arrays consisting of n integers, where each of them is in the range from 1 to 109, inclusive. Recently he has received one such array as a gift from his mother. Petya didn't like it at once. He decided to choose exactly one element from the array and replace it with another integer that also lies in the range from 1 to 109, inclusive. It is not allowed to replace a number with itself or to change no number at all. After the replacement Petya sorted the array by the numbers' non-decreasing. Now he wants to know for each position: what minimum number could occupy it after the replacement and the sorting.",[]1091"Bethany would like to tile her bathroom. The bathroom has width $$$w$$$ centimeters and length $$$l$$$ centimeters. If Bethany simply used the basic tiles of size $$$1 \times 1$$$ centimeters, she would use $$$w \cdot l$$$ of them. However, she has something different in mind.   On the interior of the floor she wants to use the $$$1 \times 1$$$ tiles. She needs exactly $$$(w-2) \cdot (l-2)$$$ of these.  On the floor boundary she wants to use tiles of size $$$1 \times a$$$ for some positive integer $$$a$$$. The tiles can also be rotated by $$$90$$$ degrees. For which values of $$$a$$$ can Bethany tile the bathroom floor as described? Note that $$$a$$$ can also be $$$1$$$. ",['math']1092"You are given three positive integers $$$a$$$, $$$b$$$, $$$c$$$ ($$$a < b < c$$$). You have to find three positive integers $$$x$$$, $$$y$$$, $$$z$$$ such that:$$$$$$x \bmod y = a,$$$$$$ $$$$$$y \bmod z = b,$$$$$$ $$$$$$z \bmod x = c.$$$$$$Here $$$p \bmod q$$$ denotes the remainder from dividing $$$p$$$ by $$$q$$$. It is possible to show that for such constraints the answer always exists.",['math']1093"You are given a huge integer $$$a$$$ consisting of $$$n$$$ digits ($$$n$$$ is between $$$1$$$ and $$$3 \cdot 10^5$$$, inclusive). It may contain leading zeros.You can swap two digits on adjacent (neighboring) positions if the swapping digits are of different parity (that is, they have different remainders when divided by $$$2$$$). For example, if $$$a = 032867235$$$ you can get the following integers in a single operation:   $$$302867235$$$ if you swap the first and the second digits;  $$$023867235$$$ if you swap the second and the third digits;  $$$032876235$$$ if you swap the fifth and the sixth digits;  $$$032862735$$$ if you swap the sixth and the seventh digits;  $$$032867325$$$ if you swap the seventh and the eighth digits. Note, that you can't swap digits on positions $$$2$$$ and $$$4$$$ because the positions are not adjacent. Also, you can't swap digits on positions $$$3$$$ and $$$4$$$ because the digits have the same parity.You can perform any number (possibly, zero) of such operations.Find the minimum integer you can obtain.Note that the resulting integer also may contain leading zeros.",[]1094"You are playing one famous sandbox game with the three-dimensional world. The map of the world can be represented as a matrix of size $$$n \times m$$$, where the height of the cell $$$(i, j)$$$ is $$$a_{i, j}$$$.You are in the cell $$$(1, 1)$$$ right now and want to get in the cell $$$(n, m)$$$. You can move only down (from the cell $$$(i, j)$$$ to the cell $$$(i + 1, j)$$$) or right (from the cell $$$(i, j)$$$ to the cell $$$(i, j + 1)$$$). There is an additional restriction: if the height of the current cell is $$$x$$$ then you can move only to the cell with height $$$x+1$$$.Before the first move you can perform several operations. During one operation, you can decrease the height of any cell by one. I.e. you choose some cell $$$(i, j)$$$ and assign (set) $$$a_{i, j} := a_{i, j} - 1$$$. Note that you can make heights less than or equal to zero. Also note that you can decrease the height of the cell $$$(1, 1)$$$.Your task is to find the minimum number of operations you have to perform to obtain at least one suitable path from the cell $$$(1, 1)$$$ to the cell $$$(n, m)$$$. It is guaranteed that the answer exists.You have to answer $$$t$$$ independent test cases.",[]1095"Marina loves Sasha. But she keeps wondering whether Sasha loves her. Of course, the best way to know it is fortune telling. There are many ways of telling fortune, but Marina has picked the easiest one. She takes in her hand one or several camomiles and tears off the petals one by one. After each petal she pronounces alternatively ""Loves"" and ""Doesn't love"", at that Marina always starts with ""Loves"". There are n camomiles growing in the field, possessing the numbers of petals equal to a1, a2, ... an. Marina wants to pick a bouquet with the maximal possible total number of petals so that the result would still be ""Loves"". Help her do that; find the maximal number of petals possible in the bouquet.",['number theory']1096"Let's consider the famous game called Boom (aka Hat) with simplified rules.There are n teams playing the game. Each team has two players. The purpose of the game is to explain the words to the teammate without using any words that contain the same root or that sound similarly. Player j from team i (1 ≤ i ≤ n, 1 ≤ j ≤ 2) is characterized by two numbers: aij and bij. The numbers correspondingly represent the skill of explaining and the skill of understanding this particular player has. Besides, m cards are used for the game. Each card has a word written on it. The card number k (1 ≤ k ≤ m) is characterized by number ck — the complexity of the word it contains.Before the game starts the cards are put in a deck and shuffled. Then the teams play in turns like that: the 1-st player of the 1-st team, the 1-st player of the 2-nd team, ... , the 1-st player of the n-th team, the 2-nd player of the 1-st team, ... , the 2-nd player of the n-th team, the 1-st player of the 1-st team and so on.Each turn continues for t seconds. It goes like that: Initially the time for each turn is t. While the time left to a player is more than 0, a player takes a card from the top of the deck and starts explaining the word it has to his teammate. The time needed for the j-th player of the i-th team to explain the word from the card k to his teammate (the q-th player of the i-th team) equals max(1, ck - (aij + biq) - dik) (if j = 1,  then q = 2,  else q = 1). The value dik is the number of seconds the i-th team has already spent explaining the word k during the previous turns. Initially, all dik equal 0. If a team manages to guess the word before the end of the turn, then the time given above is substracted from the duration of the turn, the card containing the guessed word leaves the game, the team wins one point and the game continues. If the team doesn't manage to guess the word, then the card is put at the bottom of the deck, dik increases on the amount of time of the turn, spent on explaining the word. Thus, when this team gets the very same word, they start explaining it not from the beginning, but from the point where they stopped. The game ends when words from all m cards are guessed correctly.You are given n teams and a deck of m cards. You should determine for each team, how many points it will have by the end of the game and which words the team will have guessed.",[]1097"An array $$$a_1, a_2, \ldots, a_n$$$ is good if and only if for every subsegment $$$1 \leq l \leq r \leq n$$$, the following holds: $$$a_l + a_{l + 1} + \ldots + a_r = \frac{1}{2}(a_l + a_r) \cdot (r - l + 1)$$$. You are given an array of integers $$$a_1, a_2, \ldots, a_n$$$. In one operation, you can replace any one element of this array with any real number. Find the minimum number of operations you need to make this array good.","['math', 'geometry']"1098"There is a robot on a coordinate plane. Initially, the robot is located at the point $$$(0, 0)$$$. Its path is described as a string $$$s$$$ of length $$$n$$$ consisting of characters 'L', 'R', 'U', 'D'.Each of these characters corresponds to some move:   'L' (left): means that the robot moves from the point $$$(x, y)$$$ to the point $$$(x - 1, y)$$$;  'R' (right): means that the robot moves from the point $$$(x, y)$$$ to the point $$$(x + 1, y)$$$;  'U' (up): means that the robot moves from the point $$$(x, y)$$$ to the point $$$(x, y + 1)$$$;  'D' (down): means that the robot moves from the point $$$(x, y)$$$ to the point $$$(x, y - 1)$$$. The company that created this robot asked you to optimize the path of the robot somehow. To do this, you can remove any non-empty substring of the path. But this company doesn't want their customers to notice the change in the robot behavior. It means that if before the optimization the robot ended its path at the point $$$(x_e, y_e)$$$, then after optimization (i.e. removing some single substring from $$$s$$$) the robot also ends its path at the point $$$(x_e, y_e)$$$.This optimization is a low-budget project so you need to remove the shortest possible non-empty substring to optimize the robot's path such that the endpoint of his path doesn't change. It is possible that you can't optimize the path. Also, it is possible that after the optimization the target path is an empty string (i.e. deleted substring is the whole string $$$s$$$).Recall that the substring of $$$s$$$ is such string that can be obtained from $$$s$$$ by removing some amount of characters (possibly, zero) from the prefix and some amount of characters (possibly, zero) from the suffix. For example, the substrings of ""LURLLR"" are ""LU"", ""LR"", ""LURLLR"", ""URL"", but not ""RR"" and ""UL"".You have to answer $$$t$$$ independent test cases.",[]1099"As their story unravels, a timeless tale is told once again...Shirahime, a friend of Mocha's, is keen on playing the music game Arcaea and sharing Mocha interesting puzzles to solve. This day, Shirahime comes up with a new simple puzzle and wants Mocha to solve them. However, these puzzles are too easy for Mocha to solve, so she wants you to solve them and tell her the answers. The puzzles are described as follow.There are $$$n$$$ squares arranged in a row, and each of them can be painted either red or blue.Among these squares, some of them have been painted already, and the others are blank. You can decide which color to paint on each blank square.Some pairs of adjacent squares may have the same color, which is imperfect. We define the imperfectness as the number of pairs of adjacent squares that share the same color.For example, the imperfectness of ""BRRRBBR"" is $$$3$$$, with ""BB"" occurred once and ""RR"" occurred twice.Your goal is to minimize the imperfectness and print out the colors of the squares after painting. ",[]1100"On the great island of Baltia, there live $$$N$$$ people, numbered from $$$1$$$ to $$$N$$$. There are exactly $$$M$$$ pairs of people that are friends with each other. The people of Baltia want to organize a successful party, but they have very strict rules on what a party is and when the party is successful. On the island of Baltia, a party is a gathering of exactly $$$5$$$ people. The party is considered to be successful if either all the people at the party are friends with each other (so that they can all talk to each other without having to worry about talking to someone they are not friends with) or no two people at the party are friends with each other (so that everyone can just be on their phones without anyone else bothering them). Please help the people of Baltia organize a successful party or tell them that it's impossible to do so.","['math', 'probabilities']"1101"Alice has a birthday today, so she invited home her best friend Bob. Now Bob needs to find a way to commute to the Alice's home.In the city in which Alice and Bob live, the first metro line is being built. This metro line contains $$$n$$$ stations numbered from $$$1$$$ to $$$n$$$. Bob lives near the station with number $$$1$$$, while Alice lives near the station with number $$$s$$$. The metro line has two tracks. Trains on the first track go from the station $$$1$$$ to the station $$$n$$$ and trains on the second track go in reverse direction. Just after the train arrives to the end of its track, it goes to the depot immediately, so it is impossible to travel on it after that.Some stations are not yet open at all and some are only partially open — for each station and for each track it is known whether the station is closed for that track or not. If a station is closed for some track, all trains going in this track's direction pass the station without stopping on it.When the Bob got the information on opened and closed stations, he found that traveling by metro may be unexpectedly complicated. Help Bob determine whether he can travel to the Alice's home by metro or he should search for some other transport.",['graphs']1102You are a coach of a group consisting of $$$n$$$ students. The $$$i$$$-th student has programming skill $$$a_i$$$. All students have distinct programming skills. You want to divide them into teams in such a way that:  No two students $$$i$$$ and $$$j$$$ such that $$$|a_i - a_j| = 1$$$ belong to the same team (i.e. skills of each pair of students in the same team have the difference strictly greater than $$$1$$$);  the number of teams is the minimum possible. You have to answer $$$q$$$ independent queries.,['math']1103"Julia is conducting an experiment in her lab. She placed several luminescent bacterial colonies in a horizontal testtube. Different types of bacteria can be distinguished by the color of light they emit. Julia marks types of bacteria with small Latin letters ""a"", ..., ""z"".The testtube is divided into n consecutive regions. Each region is occupied by a single colony of a certain bacteria type at any given moment. Hence, the population of the testtube at any moment can be described by a string of n Latin characters.Sometimes a colony can decide to conquer another colony in one of the adjacent regions. When that happens, the attacked colony is immediately eliminated and replaced by a colony of the same type as the attacking colony, while the attacking colony keeps its type. Note that a colony can only attack its neighbours within the boundaries of the testtube. At any moment, at most one attack can take place.For example, consider a testtube with population ""babb"". There are six options for an attack that may happen next: the first colony attacks the second colony (1 → 2), the resulting population is ""bbbb""; 2 → 1, the result is ""aabb""; 2 → 3, the result is ""baab""; 3 → 2, the result is ""bbbb"" (note that the result is the same as the first option); 3 → 4 or 4 → 3, the population does not change.The pattern of attacks is rather unpredictable. Julia is now wondering how many different configurations of bacteria in the testtube she can obtain after a sequence of attacks takes place (it is possible that no attacks will happen at all). Since this number can be large, find it modulo 109 + 7.",[]1104"Pay attention to the non-standard memory limit in this problem.In order to cut off efficient solutions from inefficient ones in this problem, the time limit is rather strict. Prefer to use compiled statically typed languages (e.g. C++). If you use Python, then submit solutions on PyPy. Try to write an efficient solution.The array $$$a=[a_1, a_2, \ldots, a_n]$$$ ($$$1 \le a_i \le n$$$) is given. Its element $$$a_i$$$ is called special if there exists a pair of indices $$$l$$$ and $$$r$$$ ($$$1 \le l < r \le n$$$) such that $$$a_i = a_l + a_{l+1} + \ldots + a_r$$$. In other words, an element is called special if it can be represented as the sum of two or more consecutive elements of an array (no matter if they are special or not).Print the number of special elements of the given array $$$a$$$.For example, if $$$n=9$$$ and $$$a=[3,1,4,1,5,9,2,6,5]$$$, then the answer is $$$5$$$:  $$$a_3=4$$$ is a special element, since $$$a_3=4=a_1+a_2=3+1$$$;  $$$a_5=5$$$ is a special element, since $$$a_5=5=a_2+a_3=1+4$$$;  $$$a_6=9$$$ is a special element, since $$$a_6=9=a_1+a_2+a_3+a_4=3+1+4+1$$$;  $$$a_8=6$$$ is a special element, since $$$a_8=6=a_2+a_3+a_4=1+4+1$$$;  $$$a_9=5$$$ is a special element, since $$$a_9=5=a_2+a_3=1+4$$$. Please note that some of the elements of the array $$$a$$$ may be equal — if several elements are equal and special, then all of them should be counted in the answer.",[]1105"After bracket sequences Arthur took up number theory. He has got a new favorite sequence of length n (a1, a2, ..., an), consisting of integers and integer k, not exceeding n.This sequence had the following property: if you write out the sums of all its segments consisting of k consecutive elements (a1  +  a2 ...  +  ak,  a2  +  a3  +  ...  +  ak + 1,  ...,  an - k + 1  +  an - k + 2  +  ...  +  an), then those numbers will form strictly increasing sequence.For example, for the following sample: n = 5,  k = 3,  a = (1,  2,  4,  5,  6) the sequence of numbers will look as follows: (1  +  2  +  4,  2  +  4  +  5,  4  +  5  +  6) = (7,  11,  15), that means that sequence a meets the described property. Obviously the sequence of sums will have n - k + 1 elements.Somebody (we won't say who) replaced some numbers in Arthur's sequence by question marks (if this number is replaced, it is replaced by exactly one question mark). We need to restore the sequence so that it meets the required property and also minimize the sum |ai|, where |ai| is the absolute value of ai.",['math']1106"There are $$$n$$$ of independent carriages on the rails. The carriages are numbered from left to right from $$$1$$$ to $$$n$$$. The carriages are not connected to each other. The carriages move to the left, so that the carriage with number $$$1$$$ moves ahead of all of them.The $$$i$$$-th carriage has its own engine, which can accelerate the carriage to $$$a_i$$$ km/h, but the carriage cannot go faster than the carriage in front of it. See example for explanation.All carriages start moving to the left at the same time, and they naturally form trains. We will call trains — consecutive moving carriages having the same speed.For example, we have $$$n=5$$$ carriages and array $$$a = [10, 13, 5, 2, 6]$$$. Then the final speeds of the carriages will be $$$[10, 10, 5, 2, 2]$$$. Respectively, $$$3$$$ of the train will be formed.There are also messages saying that some engine has been corrupted:  message ""k d"" means that the speed of the $$$k$$$-th carriage has decreased by $$$d$$$ (that is, there has been a change in the maximum speed of the carriage $$$a_k = a_k - d$$$).  Messages arrive sequentially, the processing of the next message takes into account the changes from all previous messages.After each message determine the number of formed trains.",[]1107"The elections in which three candidates participated have recently ended. The first candidate received $$$a$$$ votes, the second one received $$$b$$$ votes, the third one received $$$c$$$ votes. For each candidate, solve the following problem: how many votes should be added to this candidate so that he wins the election (i.e. the number of votes for this candidate was strictly greater than the number of votes for any other candidate)?Please note that for each candidate it is necessary to solve this problem independently, i.e. the added votes for any candidate do not affect the calculations when getting the answer for the other two candidates.",['math']1108"Dreamoon has a string s and a pattern string p. He first removes exactly x characters from s obtaining string s' as a result. Then he calculates  that is defined as the maximal number of non-overlapping substrings equal to p that can be found in s'. He wants to make this number as big as possible.More formally, let's define  as maximum value of  over all s' that can be obtained by removing exactly x characters from s. Dreamoon wants to know  for all x from 0 to |s| where |s| denotes the length of string s.",['strings']1109"You are given $$$n$$$ segments on a coordinate axis $$$OX$$$. The $$$i$$$-th segment has borders $$$[l_i; r_i]$$$. All points $$$x$$$, for which $$$l_i \le x \le r_i$$$ holds, belong to the $$$i$$$-th segment.Your task is to choose the maximum by size (the number of segments) subset of the given set of segments such that each pair of segments in this subset either non-intersecting or one of them lies inside the other one.Two segments $$$[l_i; r_i]$$$ and $$$[l_j; r_j]$$$ are non-intersecting if they have no common points. For example, segments $$$[1; 2]$$$ and $$$[3; 4]$$$, $$$[1; 3]$$$ and $$$[5; 5]$$$ are non-intersecting, while segments $$$[1; 2]$$$ and $$$[2; 3]$$$, $$$[1; 2]$$$ and $$$[2; 2]$$$ are intersecting.The segment $$$[l_i; r_i]$$$ lies inside the segment $$$[l_j; r_j]$$$ if $$$l_j \le l_i$$$ and $$$r_i \le r_j$$$. For example, segments $$$[2; 2]$$$, $$$[2, 3]$$$, $$$[3; 4]$$$ and $$$[2; 4]$$$ lie inside the segment $$$[2; 4]$$$, while $$$[2; 5]$$$ and $$$[1; 4]$$$ are not.You have to answer $$$t$$$ independent test cases.",['graphs']1110"This is an interactive problem.We have hidden an integer $$$1 \le X \le 10^{9}$$$. You don't have to guess this number. You have to find the number of divisors of this number, and you don't even have to find the exact number: your answer will be considered correct if its absolute error is not greater than 7 or its relative error is not greater than $$$0.5$$$. More formally, let your answer be $$$ans$$$ and the number of divisors of $$$X$$$ be $$$d$$$, then your answer will be considered correct if at least one of the two following conditions is true: $$$| ans - d | \le 7$$$; $$$\frac{1}{2} \le \frac{ans}{d} \le 2$$$.You can make at most $$$22$$$ queries. One query consists of one integer $$$1 \le Q \le 10^{18}$$$. In response, you will get $$$gcd(X, Q)$$$ — the greatest common divisor of $$$X$$$ and $$$Q$$$.The number $$$X$$$ is fixed before all queries. In other words, interactor is not adaptive.Let's call the process of guessing the number of divisors of number $$$X$$$ a game. In one test you will have to play $$$T$$$ independent games, that is, guess the number of divisors $$$T$$$ times for $$$T$$$ independent values of $$$X$$$.",['number theory']1111"Anna is a girl so brave that she is loved by everyone in the city and citizens love her cookies. She is planning to hold a party with cookies. Now she has $$$a$$$ vanilla cookies and $$$b$$$ chocolate cookies for the party.She invited $$$n$$$ guests of the first type and $$$m$$$ guests of the second type to the party. They will come to the party in some order. After coming to the party, each guest will choose the type of cookie (vanilla or chocolate) to eat. There is a difference in the way how they choose that type:If there are $$$v$$$ vanilla cookies and $$$c$$$ chocolate cookies at the moment, when the guest comes, then  if the guest of the first type: if $$$v>c$$$ the guest selects a vanilla cookie. Otherwise, the guest selects a chocolate cookie.  if the guest of the second type: if $$$v>c$$$ the guest selects a chocolate cookie. Otherwise, the guest selects a vanilla cookie. After that:  If there is at least one cookie of the selected type, the guest eats one.  Otherwise (there are no cookies of the selected type), the guest gets angry and returns to home. Anna wants to know if there exists some order of guests, such that no one guest gets angry. Your task is to answer her question.",['math']1112"  William arrived at a conference dedicated to cryptocurrencies. Networking, meeting new people, and using friends' connections are essential to stay up to date with the latest news from the world of cryptocurrencies.The conference has $$$n$$$ participants, who are initially unfamiliar with each other. William can introduce any two people, $$$a$$$ and $$$b$$$, who were not familiar before, to each other. William has $$$d$$$ conditions, $$$i$$$'th of which requires person $$$x_i$$$ to have a connection to person $$$y_i$$$. Formally, two people $$$x$$$ and $$$y$$$ have a connection if there is such a chain $$$p_1=x, p_2, p_3, \dots, p_k=y$$$ for which for all $$$i$$$ from $$$1$$$ to $$$k - 1$$$ it's true that two people with numbers $$$p_i$$$ and $$$p_{i + 1}$$$ know each other.For every $$$i$$$ ($$$1 \le i \le d$$$) William wants you to calculate the maximal number of acquaintances one person can have, assuming that William satisfied all conditions from $$$1$$$ and up to and including $$$i$$$ and performed exactly $$$i$$$ introductions. The conditions are being checked after William performed $$$i$$$ introductions. The answer for each $$$i$$$ must be calculated independently. It means that when you compute an answer for $$$i$$$, you should assume that no two people have been introduced to each other yet.","['graphs', 'trees']"1113"This problem is the most boring one you've ever seen. Given a sequence of integers a1, a2, ..., an and a non-negative integer h, our goal is to partition the sequence into two subsequences (not necessarily consist of continuous elements). Each element of the original sequence should be contained in exactly one of the result subsequences. Note, that one of the result subsequences can be empty.Let's define function f(ai, aj) on pairs of distinct elements (that is i ≠ j) in the original sequence. If ai and aj are in the same subsequence in the current partition then f(ai, aj) = ai + aj otherwise f(ai, aj) = ai + aj + h. Consider all possible values of the function f for some partition. We'll call the goodness of this partiotion the difference between the maximum value of function f and the minimum value of function f.Your task is to find a partition of the given sequence a that have the minimal possible goodness among all possible partitions.",[]1114Ania has a large integer $$$S$$$. Its decimal representation has length $$$n$$$ and doesn't contain any leading zeroes. Ania is allowed to change at most $$$k$$$ digits of $$$S$$$. She wants to do it in such a way that $$$S$$$ still won't contain any leading zeroes and it'll be minimal possible. What integer will Ania finish with?,[]1115"You are given an array $$$a$$$ of $$$n$$$ integers. Also you are given $$$m$$$ subsegments of that array. The left and the right endpoints of the $$$j$$$-th segment are $$$l_j$$$ and $$$r_j$$$ respectively.You are allowed to make no more than one operation. In that operation you choose any subsegment of the array $$$a$$$ and replace each value on this segment with any integer (you are also allowed to keep elements the same).You have to apply this operation so that for the given $$$m$$$ segments, the elements on each segment are distinct. More formally, for each $$$1 \le j \le m$$$ all elements $$$a_{l_{j}}, a_{l_{j}+1}, \ldots, a_{r_{j}-1}, a_{r_{j}}$$$ should be distinct.You don't want to use the operation on a big segment, so you have to find the smallest length of a segment, so that you can apply the operation to this segment and meet the above-mentioned conditions. If it is not needed to use this operation, the answer is $$$0$$$.",[]1116"Lee just became Master in Codeforces, and so, he went out to buy some gifts for his friends. He bought $$$n$$$ integers, now it's time to distribute them between his friends rationally...Lee has $$$n$$$ integers $$$a_1, a_2, \ldots, a_n$$$ in his backpack and he has $$$k$$$ friends. Lee would like to distribute all integers in his backpack between his friends, such that the $$$i$$$-th friend will get exactly $$$w_i$$$ integers and each integer will be handed over to exactly one friend.Let's define the happiness of a friend as the sum of the maximum and the minimum integer he'll get.Lee would like to make his friends as happy as possible, in other words, he'd like to maximize the sum of friends' happiness. Now he asks you to calculate the maximum sum of friends' happiness.",['math']1117"  This is an interactive taskWilliam has a certain sequence of integers $$$a_1, a_2, \dots, a_n$$$ in his mind, but due to security concerns, he does not want to reveal it to you completely. William is ready to respond to no more than $$$2 \cdot n$$$ of the following questions:  What is the result of a bitwise AND of two items with indices $$$i$$$ and $$$j$$$ ($$$i \neq j$$$)  What is the result of a bitwise OR of two items with indices $$$i$$$ and $$$j$$$ ($$$i \neq j$$$) You can ask William these questions and you need to find the $$$k$$$-th smallest number of the sequence.Formally the $$$k$$$-th smallest number is equal to the number at the $$$k$$$-th place in a 1-indexed array sorted in non-decreasing order. For example in array $$$[5, 3, 3, 10, 1]$$$ $$$4$$$th smallest number is equal to $$$5$$$, and $$$2$$$nd and $$$3$$$rd are $$$3$$$.",['math']1118"Pak Chanek is playing one of his favourite board games. In the game, there is a directed graph with $$$N$$$ vertices and $$$M$$$ edges. In the graph, edge $$$i$$$ connects two different vertices $$$U_i$$$ and $$$V_i$$$ with a length of $$$W_i$$$. By using the $$$i$$$-th edge, something can move from $$$U_i$$$ to $$$V_i$$$, but not from $$$V_i$$$ to $$$U_i$$$.To play this game, initially Pak Chanek must place both of his hands onto two different vertices. In one move, he can move one of his hands to another vertex using an edge. To move a hand from vertex $$$U_i$$$ to vertex $$$V_i$$$, Pak Chanek needs a time of $$$W_i$$$ seconds. Note that Pak Chanek can only move one hand at a time. This game ends when both of Pak Chanek's hands are on the same vertex.Pak Chanek has several questions. For each $$$p$$$ satisfying $$$2 \leq p \leq N$$$, you need to find the minimum time in seconds needed for Pak Chanek to end the game if initially Pak Chanek's left hand and right hand are placed on vertex $$$1$$$ and vertex $$$p$$$, or report if it is impossible.",['graphs']1119"Ramesses knows a lot about problems involving trees (undirected connected graphs without cycles)!He created a new useful tree decomposition, but he does not know how to construct it, so he asked you for help!The decomposition is the splitting the edges of the tree in some simple paths in such a way that each two paths have at least one common vertex. Each edge of the tree should be in exactly one path.Help Remesses, find such a decomposition of the tree or derermine that there is no such decomposition.",['trees']1120"Email address in Berland is a string of the form A@B, where A and B are arbitrary strings consisting of small Latin letters. Bob is a system administrator in «Bersoft» company. He keeps a list of email addresses of the company's staff. This list is as a large string, where all addresses are written in arbitrary order, separated by commas. The same address can be written more than once.Suddenly, because of unknown reasons, all commas in Bob's list disappeared. Now Bob has a string, where all addresses are written one after another without any separators, and there is impossible to determine, where the boundaries between addresses are. Unfortunately, on the same day his chief asked him to bring the initial list of addresses. Now Bob wants to disjoin addresses in some valid way. Help him to do that.",['strings']1121"Dasha decided to have a rest after solving the problem. She had been ready to start her favourite activity — origami, but remembered the puzzle that she could not solve.   The tree is a non-oriented connected graph without cycles. In particular, there always are n - 1 edges in a tree with n vertices.The puzzle is to position the vertices at the points of the Cartesian plane with integral coordinates, so that the segments between the vertices connected by edges are parallel to the coordinate axes. Also, the intersection of segments is allowed only at their ends. Distinct vertices should be placed at different points. Help Dasha to find any suitable way to position the tree vertices on the plane.It is guaranteed that if it is possible to position the tree vertices on the plane without violating the condition which is given above, then you can do it by using points with integral coordinates which don't exceed 1018 in absolute value.","['graphs', 'trees']"1122"You are given two binary strings $$$x$$$ and $$$y$$$, which are binary representations of some two integers (let's denote these integers as $$$f(x)$$$ and $$$f(y)$$$). You can choose any integer $$$k \ge 0$$$, calculate the expression $$$s_k = f(x) + f(y) \cdot 2^k$$$ and write the binary representation of $$$s_k$$$ in reverse order (let's denote it as $$$rev_k$$$). For example, let $$$x = 1010$$$ and $$$y = 11$$$; you've chosen $$$k = 1$$$ and, since $$$2^1 = 10_2$$$, so $$$s_k = 1010_2 + 11_2 \cdot 10_2 = 10000_2$$$ and $$$rev_k = 00001$$$.For given $$$x$$$ and $$$y$$$, you need to choose such $$$k$$$ that $$$rev_k$$$ is lexicographically minimal (read notes if you don't know what does ""lexicographically"" means).It's guaranteed that, with given constraints, $$$k$$$ exists and is finite.",[]1123"Valera had two bags of potatoes, the first of these bags contains x (x ≥ 1) potatoes, and the second — y (y ≥ 1) potatoes. Valera — very scattered boy, so the first bag of potatoes (it contains x potatoes) Valera lost. Valera remembers that the total amount of potatoes (x + y) in the two bags, firstly, was not gerater than n, and, secondly, was divisible by k.Help Valera to determine how many potatoes could be in the first bag. Print all such possible numbers in ascending order.",['math']1124"You are given a circular maze such as the ones shown in the figures.    Determine if it can be solved, i.e., if there is a path which goes from the center to the outside of the maze which does not touch any wall. The maze is described by $$$n$$$ walls. Each wall can be either circular or straight.   Circular walls are described by a radius $$$r$$$, the distance from the center, and two angles $$$\theta_1, \theta_2$$$ describing the beginning and the end of the wall in the clockwise direction. Notice that swapping the two angles changes the wall.  Straight walls are described by an angle $$$\theta$$$, the direction of the wall, and two radii $$$r_1 < r_2$$$ describing the beginning and the end of the wall. Angles are measured in degrees; the angle $$$0$$$ corresponds to the upward pointing direction; and angles increase clockwise (hence the east direction corresponds to the angle $$$90$$$).",['graphs']1125"Petya loves lucky numbers very much. Everybody knows that lucky numbers are positive integers whose decimal record contains only the lucky digits 4 and 7. For example, numbers 47, 744, 4 are lucky and 5, 17, 467 are not.Petya has two strings a and b of the same length n. The strings consist only of lucky digits. Petya can perform operations of two types:   replace any one digit from string a by its opposite (i.e., replace 4 by 7 and 7 by 4);  swap any pair of digits in string a. Petya is interested in the minimum number of operations that are needed to make string a equal to string b. Help him with the task.",[]1126"Prefix function of string $$$t = t_1 t_2 \ldots t_n$$$ and position $$$i$$$ in it is defined as the length $$$k$$$ of the longest proper (not equal to the whole substring) prefix of substring $$$t_1 t_2 \ldots t_i$$$ which is also a suffix of the same substring.For example, for string $$$t = $$$ abacaba the values of the prefix function in positions $$$1, 2, \ldots, 7$$$ are equal to $$$[0, 0, 1, 0, 1, 2, 3]$$$.Let $$$f(t)$$$ be equal to the maximum value of the prefix function of string $$$t$$$ over all its positions. For example, $$$f($$$abacaba$$$) = 3$$$.You are given a string $$$s$$$. Reorder its characters arbitrarily to get a string $$$t$$$ (the number of occurrences of any character in strings $$$s$$$ and $$$t$$$ must be equal). The value of $$$f(t)$$$ must be minimized. Out of all options to minimize $$$f(t)$$$, choose the one where string $$$t$$$ is the lexicographically smallest.",['strings']1127"You are given a correct solution of the sudoku puzzle. If you don't know what is the sudoku, you can read about it here.The picture showing the correct sudoku solution:Blocks are bordered with bold black color.Your task is to change at most $$$9$$$ elements of this field (i.e. choose some $$$1 \le i, j \le 9$$$ and change the number at the position $$$(i, j)$$$ to any other number in range $$$[1; 9]$$$) to make it anti-sudoku. The anti-sudoku is the $$$9 \times 9$$$ field, in which:  Any number in this field is in range $$$[1; 9]$$$;  each row contains at least two equal elements;  each column contains at least two equal elements;  each $$$3 \times 3$$$ block (you can read what is the block in the link above) contains at least two equal elements. It is guaranteed that the answer exists.You have to answer $$$t$$$ independent test cases.",[]1128"Fox Ciel is participating in a party in Prime Kingdom. There are n foxes there (include Fox Ciel). The i-th fox is ai years old.They will have dinner around some round tables. You want to distribute foxes such that:  Each fox is sitting at some table.  Each table has at least 3 foxes sitting around it.  The sum of ages of any two adjacent foxes around each table should be a prime number. If k foxes f1, f2, ..., fk are sitting around table in clockwise order, then for 1 ≤ i ≤ k - 1: fi and fi + 1 are adjacent, and f1 and fk are also adjacent.If it is possible to distribute the foxes in the desired manner, find out a way to do that.",[]1129"This problem differs from the previous one only in the absence of the constraint on the equal length of all numbers $$$a_1, a_2, \dots, a_n$$$.A team of SIS students is going to make a trip on a submarine. Their target is an ancient treasure in a sunken ship lying on the bottom of the Great Rybinsk sea. Unfortunately, the students don't know the coordinates of the ship, so they asked Meshanya (who is a hereditary mage) to help them. He agreed to help them, but only if they solve his problem.Let's denote a function that alternates digits of two numbers $$$f(a_1 a_2 \dots a_{p - 1} a_p, b_1 b_2 \dots b_{q - 1} b_q)$$$, where $$$a_1 \dots a_p$$$ and $$$b_1 \dots b_q$$$ are digits of two integers written in the decimal notation without leading zeros.In other words, the function $$$f(x, y)$$$ alternately shuffles the digits of the numbers $$$x$$$ and $$$y$$$ by writing them from the lowest digits to the older ones, starting with the number $$$y$$$. The result of the function is also built from right to left (that is, from the lower digits to the older ones). If the digits of one of the arguments have ended, then the remaining digits of the other argument are written out. Familiarize with examples and formal definitions of the function below.For example: $$$$$$f(1111, 2222) = 12121212$$$$$$ $$$$$$f(7777, 888) = 7787878$$$$$$ $$$$$$f(33, 44444) = 4443434$$$$$$ $$$$$$f(555, 6) = 5556$$$$$$ $$$$$$f(111, 2222) = 2121212$$$$$$Formally,  if $$$p \ge q$$$ then $$$f(a_1 \dots a_p, b_1 \dots b_q) = a_1 a_2 \dots a_{p - q + 1} b_1 a_{p - q + 2} b_2 \dots a_{p - 1} b_{q - 1} a_p b_q$$$;  if $$$p < q$$$ then $$$f(a_1 \dots a_p, b_1 \dots b_q) = b_1 b_2 \dots b_{q - p} a_1 b_{q - p + 1} a_2 \dots a_{p - 1} b_{q - 1} a_p b_q$$$. Mishanya gives you an array consisting of $$$n$$$ integers $$$a_i$$$, your task is to help students to calculate $$$\sum_{i = 1}^{n}\sum_{j = 1}^{n} f(a_i, a_j)$$$ modulo $$$998\,244\,353$$$.","['math', 'number theory']"1130"Dima liked the present he got from Inna very much. He liked the present he got from Seryozha even more. Dima felt so grateful to Inna about the present that he decided to buy her n hares. Inna was very happy. She lined up the hares in a row, numbered them from 1 to n from left to right and started feeding them with carrots. Inna was determined to feed each hare exactly once. But in what order should she feed them?Inna noticed that each hare radiates joy when she feeds it. And the joy of the specific hare depends on whether Inna fed its adjacent hares before feeding it. Inna knows how much joy a hare radiates if it eats when either both of his adjacent hares are hungry, or one of the adjacent hares is full (that is, has been fed), or both of the adjacent hares are full. Please note that hares number 1 and n don't have a left and a right-adjacent hare correspondingly, so they can never have two full adjacent hares.Help Inna maximize the total joy the hares radiate. :)",[]1131"Thanks to the Doctor's help, the rebels managed to steal enough gold to launch a full-scale attack on the Empire! However, Darth Vader is looking for revenge and wants to take back his gold.The rebels have hidden the gold in various bases throughout the galaxy. Darth Vader and the Empire are looking to send out their spaceships to attack these bases.The galaxy can be represented as an undirected graph with $$$n$$$ planets (nodes) and $$$m$$$ wormholes (edges), each connecting two planets.A total of $$$s$$$ empire spaceships and $$$b$$$ rebel bases are located at different planets in the galaxy.Each spaceship is given a location $$$x$$$, denoting the index of the planet on which it is located, an attacking strength $$$a$$$, and a certain amount of fuel $$$f$$$.Each base is given a location $$$x$$$, and a defensive strength $$$d$$$.A spaceship can attack a base if both of these conditions hold:   the spaceship's attacking strength is greater or equal than the defensive strength of the base  the spaceship's fuel is greater or equal to the shortest distance, computed as the number of wormholes, between the spaceship's planet and the base's planet Vader is very particular about his attacking formations. He requires that each spaceship is to attack at most one base and that each base is to be attacked by at most one spaceship.Vader knows that the rebels have hidden $$$k$$$ gold in each base, so he will assign the spaceships to attack bases in such a way that maximizes the number of bases attacked.Therefore, for each base that is attacked, the rebels lose $$$k$$$ gold.However, the rebels have the ability to create any number of dummy bases. With the Doctor's help, these bases would exist beyond space and time, so all spaceship can reach them and attack them. Moreover, a dummy base is designed to seem irresistible: that is, it will always be attacked by some spaceship.Of course, dummy bases do not contain any gold, but creating such a dummy base costs $$$h$$$ gold.What is the minimum gold the rebels can lose if they create an optimal number of dummy bases?",['graphs']1132"Emuskald is addicted to Codeforces, and keeps refreshing the main page not to miss any changes in the ""recent actions"" list. He likes to read thread conversations where each thread consists of multiple messages.Recent actions shows a list of n different threads ordered by the time of the latest message in the thread. When a new message is posted in a thread that thread jumps on the top of the list. No two messages of different threads are ever posted at the same time.Emuskald has just finished reading all his opened threads and refreshes the main page for some more messages to feed his addiction. He notices that no new threads have appeared in the list and at the i-th place in the list there is a thread that was at the ai-th place before the refresh. He doesn't want to waste any time reading old messages so he wants to open only threads with new messages.Help Emuskald find out the number of threads that surely have new messages. A thread x surely has a new message if there is no such sequence of thread updates (posting messages) that both conditions hold:   thread x is not updated (it has no new messages);  the list order 1, 2, ..., n changes to a1, a2, ..., an. ",[]1133"In the capital city of Berland, Bertown, demonstrations are against the recent election of the King of Berland. Berland opposition, led by Mr. Ovalny, believes that the elections were not fair enough and wants to organize a demonstration at one of the squares.Bertown has n squares, numbered from 1 to n, they are numbered in the order of increasing distance between them and the city center. That is, square number 1 is central, and square number n is the farthest from the center. Naturally, the opposition wants to hold a meeting as close to the city center as possible (that is, they want an square with the minimum number).There are exactly k (k < n) days left before the demonstration. Now all squares are free. But the Bertown city administration never sleeps, and the approval of an application for the demonstration threatens to become a very complex process. The process of approval lasts several days, but every day the following procedure takes place:  The opposition shall apply to hold a demonstration at a free square (the one which isn't used by the administration).  The administration tries to move the demonstration to the worst free square left. To do this, the administration organizes some long-term activities on the square, which is specified in the application of opposition. In other words, the administration starts using the square and it is no longer free. Then the administration proposes to move the opposition demonstration to the worst free square. If the opposition has applied for the worst free square then request is accepted and administration doesn't spend money. If the administration does not have enough money to organize an event on the square in question, the opposition's application is accepted. If administration doesn't have enough money to organize activity, then rest of administration's money spends and application is accepted  If the application is not accepted, then the opposition can agree to the administration's proposal (that is, take the worst free square), or withdraw the current application and submit another one the next day. If there are no more days left before the meeting, the opposition has no choice but to agree to the proposal of City Hall. If application is accepted opposition can reject it. It means than opposition still can submit more applications later, but square remains free. In order to organize an event on the square i, the administration needs to spend ai bourles. Because of the crisis the administration has only b bourles to confront the opposition. What is the best square that the opposition can take, if the administration will keep trying to occupy the square in question each time? Note that the administration's actions always depend only on the actions of the opposition.",[]1134"You are given an array $$$a_1, a_2 \dots a_n$$$. Calculate the number of tuples $$$(i, j, k, l)$$$ such that:   $$$1 \le i < j < k < l \le n$$$;  $$$a_i = a_k$$$ and $$$a_j = a_l$$$; ",['math']1135"This problem is different from the hard version. In this version Ujan makes exactly one exchange. You can hack this problem only if you solve both problems.After struggling and failing many times, Ujan decided to try to clean up his house again. He decided to get his strings in order first.Ujan has two distinct strings $$$s$$$ and $$$t$$$ of length $$$n$$$ consisting of only of lowercase English characters. He wants to make them equal. Since Ujan is lazy, he will perform the following operation exactly once: he takes two positions $$$i$$$ and $$$j$$$ ($$$1 \le i,j \le n$$$, the values $$$i$$$ and $$$j$$$ can be equal or different), and swaps the characters $$$s_i$$$ and $$$t_j$$$. Can he succeed?Note that he has to perform this operation exactly once. He has to perform this operation.",['strings']1136"There are $$$n$$$ nodes arranged in a circle numbered from $$$1$$$ to $$$n$$$ in the clockwise order. You are also given a binary string $$$s$$$ of length $$$n$$$.Your task is to construct a tree on the given $$$n$$$ nodes satisfying the two conditions below or report that there such tree does not exist:  For each node $$$i$$$ $$$(1 \le i \le n)$$$, the degree of node is even if $$$s_i = 0$$$ and odd if $$$s_i = 1$$$.  No two edges of the tree intersect internally in the circle. The edges are allowed to intersect on the circumference.  Note that all edges are drawn as straight line segments. For example, edge $$$(u, v)$$$ in the tree is drawn as a line segment connecting $$$u$$$ and $$$v$$$ on the circle.A tree on $$$n$$$ nodes is a connected graph with $$$n - 1$$$ edges.",['trees']1137"You work in a big office. It is a 9 floor building with an elevator that can accommodate up to 4 people. It is your responsibility to manage this elevator.Today you are late, so there are queues on some floors already. For each person you know the floor where he currently is and the floor he wants to reach. Also, you know the order in which people came to the elevator.According to the company's rules, if an employee comes to the elevator earlier than another one, he has to enter the elevator earlier too (even if these employees stay on different floors). Note that the employees are allowed to leave the elevator in arbitrary order.The elevator has two commands:   Go up or down one floor. The movement takes 1 second.  Open the doors on the current floor. During this operation all the employees who have reached their destination get out of the elevator. Then all the employees on the floor get in the elevator in the order they are queued up while it doesn't contradict the company's rules and there is enough space in the elevator. Each employee spends 1 second to get inside and outside the elevator. Initially the elevator is empty and is located on the floor 1.You are interested what is the minimum possible time you need to spend to deliver all the employees to their destination. It is not necessary to return the elevator to the floor 1.",['graphs']1138"Today is Devu's birthday. For celebrating the occasion, he bought n sweets from the nearby market. He has invited his f friends. He would like to distribute the sweets among them. As he is a nice guy and the occasion is great, he doesn't want any friend to be sad, so he would ensure to give at least one sweet to each friend. He wants to celebrate it in a unique style, so he would like to ensure following condition for the distribution of sweets. Assume that he has distributed n sweets to his friends such that ith friend is given ai sweets. He wants to make sure that there should not be any positive integer x > 1, which divides every ai.Please find the number of ways he can distribute sweets to his friends in the required way. Note that the order of distribution is important, for example [1, 2] and [2, 1] are distinct distributions. As the answer could be very large, output answer modulo 1000000007 (109 + 7).To make the problem more interesting, you are given q queries. Each query contains an n, f pair. For each query please output the required number of ways modulo 1000000007 (109 + 7).",['math']1139"A and B are preparing themselves for programming contests.The University where A and B study is a set of rooms connected by corridors. Overall, the University has n rooms connected by n - 1 corridors so that you can get from any room to any other one by moving along the corridors. The rooms are numbered from 1 to n.Every day А and B write contests in some rooms of their university, and after each contest they gather together in the same room and discuss problems. A and B want the distance from the rooms where problems are discussed to the rooms where contests are written to be equal. The distance between two rooms is the number of edges on the shortest path between them.As they write contests in new rooms every day, they asked you to help them find the number of possible rooms to discuss problems for each of the following m days.",['trees']1140"Harry came to know from Dumbledore that Salazar Slytherin's locket is a horcrux. This locket was present earlier at 12 Grimmauld Place, the home of Sirius Black's mother. It was stolen from there and is now present in the Ministry of Magic in the office of Dolorous Umbridge, Harry's former Defense Against the Dark Arts teacher. Harry, Ron and Hermione are infiltrating the Ministry. Upon reaching Umbridge's office, they observed a code lock with a puzzle asking them to calculate count of magic numbers between two integers l and r (both inclusive). Harry remembered from his detention time with Umbridge that she defined a magic number as a number which when converted to a given base b, all the digits from 0 to b - 1 appear even number of times in its representation without any leading zeros.You have to answer q queries to unlock the office. Each query has three integers bi, li and ri, the base and the range for which you have to find the count of magic numbers.",[]1141"Recently you have bought a snow walking robot and brought it home. Suppose your home is a cell $$$(0, 0)$$$ on an infinite grid.You also have the sequence of instructions of this robot. It is written as the string $$$s$$$ consisting of characters 'L', 'R', 'U' and 'D'. If the robot is in the cell $$$(x, y)$$$ right now, he can move to one of the adjacent cells (depending on the current instruction).  If the current instruction is 'L', then the robot can move to the left to $$$(x - 1, y)$$$;  if the current instruction is 'R', then the robot can move to the right to $$$(x + 1, y)$$$;  if the current instruction is 'U', then the robot can move to the top to $$$(x, y + 1)$$$;  if the current instruction is 'D', then the robot can move to the bottom to $$$(x, y - 1)$$$. You've noticed the warning on the last page of the manual: if the robot visits some cell (except $$$(0, 0)$$$) twice then it breaks.So the sequence of instructions is valid if the robot starts in the cell $$$(0, 0)$$$, performs the given instructions, visits no cell other than $$$(0, 0)$$$ two or more times and ends the path in the cell $$$(0, 0)$$$. Also cell $$$(0, 0)$$$ should be visited at most two times: at the beginning and at the end (if the path is empty then it is visited only once). For example, the following sequences of instructions are considered valid: ""UD"", ""RL"", ""UUURULLDDDDLDDRRUU"", and the following are considered invalid: ""U"" (the endpoint is not $$$(0, 0)$$$) and ""UUDD"" (the cell $$$(0, 1)$$$ is visited twice).The initial sequence of instructions, however, might be not valid. You don't want your robot to break so you decided to reprogram it in the following way: you will remove some (possibly, all or none) instructions from the initial sequence of instructions, then rearrange the remaining instructions as you wish and turn on your robot to move. Your task is to remove as few instructions from the initial sequence as possible and rearrange the remaining ones so that the sequence is valid. Report the valid sequence of the maximum length you can obtain.Note that you can choose any order of remaining instructions (you don't need to minimize the number of swaps or any other similar metric).You have to answer $$$q$$$ independent test cases.",[]1142"You are given a graph with $$$n$$$ nodes and $$$m$$$ directed edges. One lowercase letter is assigned to each node. We define a path's value as the number of the most frequently occurring letter. For example, if letters on a path are ""abaca"", then the value of that path is $$$3$$$. Your task is find a path whose value is the largest.",['graphs']1143"A k-multiple free set is a set of integers where there is no pair of integers where one is equal to another integer multiplied by k. That is, there are no two integers x and y (x < y) from the set, such that y = x·k.You're given a set of n distinct positive integers. Your task is to find the size of it's largest k-multiple free subset.",[]1144"Roland loves growing flowers. He has recently grown a beautiful rose at point (0, 0) of the Cartesian coordinate system. The rose is so beautiful that Roland is afraid that the evil forces can try and steal it. To protect the rose, Roland wants to build n watch towers. Let's assume that a tower is a point on the plane at the distance of at most r from the rose. Besides, Roland assumes that the towers should be built at points with integer coordinates and the sum of squares of distances between all pairs of towers must be as large as possible. Note, that Roland may build several towers at the same point, also he may build some of them at point (0, 0).Help Roland build the towers at the integer points so that the sum of squares of distances between all towers is maximum possible. Note that the distance in this problem is defined as the Euclidian distance between points.","['math', 'geometry']"1145"Little boy Petya loves stairs very much. But he is bored from simple going up and down them — he loves jumping over several stairs at a time. As he stands on some stair, he can either jump to the next one or jump over one or two stairs at a time. But some stairs are too dirty and Petya doesn't want to step on them.Now Petya is on the first stair of the staircase, consisting of n stairs. He also knows the numbers of the dirty stairs of this staircase. Help Petya find out if he can jump through the entire staircase and reach the last stair number n without touching a dirty stair once.One has to note that anyway Petya should step on the first and last stairs, so if the first or the last stair is dirty, then Petya cannot choose a path with clean steps only.",[]1146"Kuroni isn't good at economics. So he decided to found a new financial pyramid called Antihype. It has the following rules:  You can join the pyramid for free and get $$$0$$$ coins.  If you are already a member of Antihype, you can invite your friend who is currently not a member of Antihype, and get a number of coins equal to your age (for each friend you invite). $$$n$$$ people have heard about Antihype recently, the $$$i$$$-th person's age is $$$a_i$$$. Some of them are friends, but friendship is a weird thing now: the $$$i$$$-th person is a friend of the $$$j$$$-th person if and only if $$$a_i \text{ AND } a_j = 0$$$, where $$$\text{AND}$$$ denotes the bitwise AND operation.Nobody among the $$$n$$$ people is a member of Antihype at the moment. They want to cooperate to join and invite each other to Antihype in a way that maximizes their combined gainings. Could you help them? ",['graphs']1147"The Cybermen solved that first test much quicker than the Daleks. Luckily for us, the Daleks were angry (shocking!) and they destroyed some of the Cybermen.After the fighting stopped, Heidi gave them another task to waste their time on.There are $$$n$$$ points on a plane. Given a radius $$$r$$$, find the maximum number of points that can be covered by an $$$L^1$$$-ball with radius $$$r$$$.An $$$L^1$$$-ball with radius $$$r$$$ and center $$$(x_0, y_0)$$$ in a 2D-plane is defined as the set of points $$$(x, y)$$$ such that the Manhattan distance between $$$(x_0, y_0)$$$ and $$$(x, y)$$$ is at most $$$r$$$.Manhattan distance between $$$(x_0, y_0)$$$ and $$$(x, y)$$$ is defined as $$$|x - x_0| + |y - y_0|$$$.",[]1148"A coordinate line has n segments, the i-th segment starts at the position li and ends at the position ri. We will denote such a segment as [li, ri].You have suggested that one of the defined segments covers all others. In other words, there is such segment in the given set, which contains all other ones. Now you want to test your assumption. Find in the given set the segment which covers all other segments, and print its number. If such a segment doesn't exist, print -1.Formally we will assume that segment [a, b] covers segment [c, d], if they meet this condition a ≤ c ≤ d ≤ b. ",[]1149There are n boys and m girls studying in the class. They should stand in a line so that boys and girls alternated there as much as possible. Let's assume that positions in the line are indexed from left to right by numbers from 1 to n + m. Then the number of integers i (1 ≤ i < n + m) such that positions with indexes i and i + 1 contain children of different genders (position i has a girl and position i + 1 has a boy or vice versa) must be as large as possible. Help the children and tell them how to form the line.,[]1150"Valerian was captured by Shapur. The victory was such a great one that Shapur decided to carve a scene of Valerian's defeat on a mountain. So he had to find the best place to make his victory eternal!He decided to visit all n cities of Persia to find the best available mountain, but after the recent war he was too tired and didn't want to traverse a lot. So he wanted to visit each of these n cities at least once with smallest possible traverse. Persian cities are connected with bidirectional roads. You can go from any city to any other one using these roads and there is a unique path between each two cities.All cities are numbered 1 to n. Shapur is currently in the city 1 and he wants to visit all other cities with minimum possible traverse. He can finish his travels in any city.Help Shapur find how much He should travel.","['graphs', 'trees']"1151"During a break in the buffet of the scientific lyceum of the Kingdom of Kremland, there was formed a queue of $$$n$$$ high school students numbered from $$$1$$$ to $$$n$$$. Initially, each student $$$i$$$ is on position $$$i$$$. Each student $$$i$$$ is characterized by two numbers — $$$a_i$$$ and $$$b_i$$$. Dissatisfaction of the person $$$i$$$ equals the product of $$$a_i$$$ by the number of people standing to the left of his position, add the product $$$b_i$$$ by the number of people standing to the right of his position. Formally, the dissatisfaction of the student $$$i$$$, which is on the position $$$j$$$, equals $$$a_i \cdot (j-1) + b_i \cdot (n-j)$$$.The director entrusted Stas with the task: rearrange the people in the queue so that minimize the total dissatisfaction.Although Stas is able to solve such problems, this was not given to him. He turned for help to you.",['math']1152"Polycarp has n dice d1, d2, ..., dn. The i-th dice shows numbers from 1 to di. Polycarp rolled all the dice and the sum of numbers they showed is A. Agrippina didn't see which dice showed what number, she knows only the sum A and the values d1, d2, ..., dn. However, she finds it enough to make a series of statements of the following type: dice i couldn't show number r. For example, if Polycarp had two six-faced dice and the total sum is A = 11, then Agrippina can state that each of the two dice couldn't show a value less than five (otherwise, the remaining dice must have a value of at least seven, which is impossible).For each dice find the number of values for which it can be guaranteed that the dice couldn't show these values if the sum of the shown values is A.",['math']1153"Little Vasya's uncle is a postman. The post offices are located on one circular road. Besides, each post office has its own gas station located next to it. Petya's uncle works as follows: in the morning he should leave the house and go to some post office. In the office he receives a portion of letters and a car. Then he must drive in the given car exactly one round along the circular road and return to the starting post office (the uncle can drive along the circle in any direction, counterclockwise or clockwise). Besides, since the car belongs to the city post, it should also be fuelled with gasoline only at the Post Office stations. The total number of stations equals to n. One can fuel the car at the i-th station with no more than ai liters of gasoline. Besides, one can fuel the car no more than once at each station. Also, the distance between the 1-st and the 2-nd station is b1 kilometers, the distance between the 2-nd and the 3-rd one is b2 kilometers, ..., between the (n - 1)-th and the n-th ones the distance is bn - 1 kilometers and between the n-th and the 1-st one the distance is bn kilometers. Petya's uncle's high-tech car uses only one liter of gasoline per kilometer. It is known that the stations are located so that the sum of all ai is equal to the sum of all bi. The i-th gas station and i-th post office are very close, so the distance between them is 0 kilometers.Thus, it becomes clear that if we start from some post offices, then it is not always possible to drive one round along a circular road. The uncle faces the following problem: to what stations can he go in the morning to be able to ride exactly one circle along the circular road and visit all the post offices that are on it?Petya, who used to attend programming classes, has volunteered to help his uncle, but his knowledge turned out to be not enough, so he asks you to help him write the program that will solve the posed problem.",[]1154"You've got an n × m pixel picture. Each pixel can be white or black. Your task is to change the colors of as few pixels as possible to obtain a barcode picture.A picture is a barcode if the following conditions are fulfilled:   All pixels in each column are of the same color.  The width of each monochrome vertical line is at least x and at most y pixels. In other words, if we group all neighbouring columns of the pixels with equal color, the size of each group can not be less than x or greater than y. ",[]1155"Bashar was practicing for the national programming contest. Because of sitting too much in front of the computer without doing physical movements and eating a lot Bashar became much fatter. Bashar is going to quit programming after the national contest and he is going to become an actor (just like his father), so he should lose weight.In order to lose weight, Bashar is going to run for $$$k$$$ kilometers. Bashar is going to run in a place that looks like a grid of $$$n$$$ rows and $$$m$$$ columns. In this grid there are two one-way roads of one-kilometer length between each pair of adjacent by side cells, one road is going from the first cell to the second one, and the other road is going from the second cell to the first one. So, there are exactly $$$(4 n m - 2n - 2m)$$$ roads.Let's take, for example, $$$n = 3$$$ and $$$m = 4$$$. In this case, there are $$$34$$$ roads. It is the picture of this case (arrows describe roads):Bashar wants to run by these rules:  He starts at the top-left cell in the grid;  In one move Bashar may go up (the symbol 'U'), down (the symbol 'D'), left (the symbol 'L') or right (the symbol 'R'). More formally, if he stands in the cell in the row $$$i$$$ and in the column $$$j$$$, i.e. in the cell $$$(i, j)$$$ he will move to:   in the case 'U' to the cell $$$(i-1, j)$$$;  in the case 'D' to the cell $$$(i+1, j)$$$;  in the case 'L' to the cell $$$(i, j-1)$$$;  in the case 'R' to the cell $$$(i, j+1)$$$;   He wants to run exactly $$$k$$$ kilometers, so he wants to make exactly $$$k$$$ moves;  Bashar can finish in any cell of the grid;  He can't go out of the grid so at any moment of the time he should be on some cell;  Bashar doesn't want to get bored while running so he must not visit the same road twice. But he can visit the same cell any number of times. Bashar asks you if it is possible to run by such rules. If it is possible, you should tell him how should he run.You should give him $$$a$$$ steps to do and since Bashar can't remember too many steps, $$$a$$$ should not exceed $$$3000$$$. In every step, you should give him an integer $$$f$$$ and a string of moves $$$s$$$ of length at most $$$4$$$ which means that he should repeat the moves in the string $$$s$$$ for $$$f$$$ times. He will perform the steps in the order you print them.For example, if the steps are $$$2$$$ RUD, $$$3$$$ UUL then the moves he is going to move are RUD $$$+$$$ RUD $$$+$$$ UUL $$$+$$$ UUL $$$+$$$ UUL $$$=$$$ RUDRUDUULUULUUL.Can you help him and give him a correct sequence of moves such that the total distance he will run is equal to $$$k$$$ kilometers or say, that it is impossible?",['graphs']1156"Ivan had string s consisting of small English letters. However, his friend Julia decided to make fun of him and hid the string s. Ivan preferred making a new string to finding the old one. Ivan knows some information about the string s. Namely, he remembers, that string ti occurs in string s at least ki times or more, he also remembers exactly ki positions where the string ti occurs in string s: these positions are xi, 1, xi, 2, ..., xi, ki. He remembers n such strings ti.You are to reconstruct lexicographically minimal string s such that it fits all the information Ivan remembers. Strings ti and string s consist of small English letters only.",['strings']1157"This is an easy version of the problem. The difference between the easy and hard versions is that in this version, you can output any permutation with the smallest weight.You are given a permutation $$$p_1, p_2, \ldots, p_n$$$ of integers from $$$1$$$ to $$$n$$$.Let's define the weight of the permutation $$$q_1, q_2, \ldots, q_n$$$ of integers from $$$1$$$ to $$$n$$$ as $$$$$$|q_1 - p_{q_{2}}| + |q_2 - p_{q_{3}}| + \ldots + |q_{n-1} - p_{q_{n}}| + |q_n - p_{q_{1}}|$$$$$$You want your permutation to be as lightweight as possible. Find any permutation $$$q$$$ with the smallest possible weight.",[]1158"Note that this is the first problem of the two similar problems. You can hack this problem only if you solve both problems.You are given a tree with $$$n$$$ nodes. In the beginning, $$$0$$$ is written on all edges. In one operation, you can choose any $$$2$$$ distinct leaves $$$u$$$, $$$v$$$ and any real number $$$x$$$ and add $$$x$$$ to values written on all edges on the simple path between $$$u$$$ and $$$v$$$.For example, on the picture below you can see the result of applying two operations to the graph: adding $$$2$$$ on the path from $$$7$$$ to $$$6$$$, and then adding $$$-0.5$$$ on the path from $$$4$$$ to $$$5$$$.   Is it true that for any configuration of real numbers written on edges, we can achieve it with a finite number of operations?Leaf is a node of a tree of degree $$$1$$$. Simple path is a path that doesn't contain any node twice.",['trees']1159"This is the hard version of the problem. The only difference between the easy and the hard versions are removal queries, they are present only in the hard version.""Interplanetary Software, Inc."" together with ""Robots of Cydonia, Ltd."" has developed and released robot cats. These electronic pets can meow, catch mice and entertain the owner in various ways.The developers from ""Interplanetary Software, Inc."" have recently decided to release a software update for these robots. After the update, the cats must solve the problems about bracket sequences. One of the problems is described below.  First, we need to learn a bit of bracket sequence theory. Consider the strings that contain characters ""("", "")"" and ""."". Call a string regular bracket sequence (RBS), if it can be transformed to an empty string by one or more operations of removing either single ""."" characters, or a continuous substring ""()"". For instance, the string ""(()(.))"" is an RBS, as it can be transformed to an empty string with the following sequence of removals: ""(()(.))"" $$$\rightarrow$$$ ""(()())"" $$$\rightarrow$$$ ""(())"" $$$\rightarrow$$$ ""()"" $$$\rightarrow$$$ """". We got an empty string, so the initial string was an RBS. At the same time, the string "")("" is not an RBS, as it is not possible to apply such removal operations to it.An RBS is simple if this RBS is not empty, doesn't start with ""."", and doesn't end with ""."".Denote the substring of the string $$$s$$$ as its sequential subsegment. In particular, $$$s[l\dots r] = s_ls_{l+1}\dots s_r$$$, where $$$s_i$$$ is the $$$i$$$-th character of the string $$$s$$$.Now, move on to the problem statement itself. You are given a string $$$s$$$, initially consisting of characters ""("" and "")"". You need to answer the following queries:  Given two indices, $$$l$$$ and $$$r$$$ ($$$1 \le l < r \le n$$$). It's guaranteed that the $$$l$$$-th character is equal to ""("", the $$$r$$$-th character is equal to "")"", and the characters between them are equal to ""."". Then the $$$l$$$-th and the $$$r$$$-th characters must be set to ""."".  Given two indices, $$$l$$$ and $$$r$$$ ($$$1 \le l < r \le n$$$), and it's guaranteed that the substring $$$s[l\dots r]$$$ is a simple RBS. You need to find the number of substrings in $$$s[l\dots r]$$$ such that they are simple RBS. In other words, find the number of index pairs $$$i$$$, $$$j$$$ such that $$$l \le i < j \le r$$$ and $$$s[i\dots j]$$$ is a simple RBS. You are an employee in ""Interplanetary Software, Inc."" and you were given the task to teach the cats to solve the problem above, after the update.","['graphs', 'trees']"1160"You are given a string $$$s$$$ consisting only of lowercase Latin letters.You can rearrange all letters of this string as you wish. Your task is to obtain a good string by rearranging the letters of the given string or report that it is impossible to do it.Let's call a string good if it is not a palindrome. Palindrome is a string which is read from left to right the same as from right to left. For example, strings ""abacaba"", ""aa"" and ""z"" are palindromes and strings ""bba"", ""xd"" are not.You have to answer $$$t$$$ independent queries.",['strings']1161Yaroslav has an array that consists of n integers. In one second Yaroslav can swap two neighboring array elements. Now Yaroslav is wondering if he can obtain an array where any two neighboring elements would be distinct in a finite time.Help Yaroslav.,['math']1162"Ezzat has an array of $$$n$$$ integers (maybe negative). He wants to split it into two non-empty subsequences $$$a$$$ and $$$b$$$, such that every element from the array belongs to exactly one subsequence, and the value of $$$f(a) + f(b)$$$ is the maximum possible value, where $$$f(x)$$$ is the average of the subsequence $$$x$$$. A sequence $$$x$$$ is a subsequence of a sequence $$$y$$$ if $$$x$$$ can be obtained from $$$y$$$ by deletion of several (possibly, zero or all) elements.The average of a subsequence is the sum of the numbers of this subsequence divided by the size of the subsequence.For example, the average of $$$[1,5,6]$$$ is $$$(1+5+6)/3 = 12/3 = 4$$$, so $$$f([1,5,6]) = 4$$$.",['math']1163"AquaMoon has two binary sequences $$$a$$$ and $$$b$$$, which contain only $$$0$$$ and $$$1$$$. AquaMoon can perform the following two operations any number of times ($$$a_1$$$ is the first element of $$$a$$$, $$$a_2$$$ is the second element of $$$a$$$, and so on): Operation 1: if $$$a$$$ contains at least two elements, change $$$a_2$$$ to $$$\operatorname{min}(a_1,a_2)$$$, and remove the first element of $$$a$$$. Operation 2: if $$$a$$$ contains at least two elements, change $$$a_2$$$ to $$$\operatorname{max}(a_1,a_2)$$$, and remove the first element of $$$a$$$.Note that after a removal of the first element of $$$a$$$, the former $$$a_2$$$ becomes the first element of $$$a$$$, the former $$$a_3$$$ becomes the second element of $$$a$$$ and so on, and the length of $$$a$$$ reduces by one.Determine if AquaMoon can make $$$a$$$ equal to $$$b$$$ by using these operations.",[]1164"Vasya got really tired of these credits (from problem F) and now wants to earn the money himself! He decided to make a contest to gain a profit.Vasya has $$$n$$$ problems to choose from. They are numbered from $$$1$$$ to $$$n$$$. The difficulty of the $$$i$$$-th problem is $$$d_i$$$. Moreover, the problems are given in the increasing order by their difficulties. The difficulties of all tasks are pairwise distinct. In order to add the $$$i$$$-th problem to the contest you need to pay $$$c_i$$$ burles to its author. For each problem in the contest Vasya gets $$$a$$$ burles.In order to create a contest he needs to choose a consecutive subsegment of tasks.So the total earnings for the contest are calculated as follows:   if Vasya takes problem $$$i$$$ to the contest, he needs to pay $$$c_i$$$ to its author;  for each problem in the contest Vasya gets $$$a$$$ burles;  let $$$gap(l, r) = \max\limits_{l \le i < r} (d_{i + 1} - d_i)^2$$$. If Vasya takes all the tasks with indices from $$$l$$$ to $$$r$$$ to the contest, he also needs to pay $$$gap(l, r)$$$. If $$$l = r$$$ then $$$gap(l, r) = 0$$$. Calculate the maximum profit that Vasya can earn by taking a consecutive segment of tasks.",[]1165"A group of n schoolboys decided to ride bikes. As nobody of them has a bike, the boys need to rent them.The renting site offered them m bikes. The renting price is different for different bikes, renting the j-th bike costs pj rubles.In total, the boys' shared budget is a rubles. Besides, each of them has his own personal money, the i-th boy has bi personal rubles. The shared budget can be spent on any schoolchildren arbitrarily, but each boy's personal money can be spent on renting only this boy's bike.Each boy can rent at most one bike, one cannot give his bike to somebody else.What maximum number of schoolboys will be able to ride bikes? What minimum sum of personal money will they have to spend in total to let as many schoolchildren ride bikes as possible?",[]1166"You are given a tuple generator $$$f^{(k)} = (f_1^{(k)}, f_2^{(k)}, \dots, f_n^{(k)})$$$, where $$$f_i^{(k)} = (a_i \cdot f_i^{(k - 1)} + b_i) \bmod p_i$$$ and $$$f^{(0)} = (x_1, x_2, \dots, x_n)$$$. Here $$$x \bmod y$$$ denotes the remainder of $$$x$$$ when divided by $$$y$$$. All $$$p_i$$$ are primes.One can see that with fixed sequences $$$x_i$$$, $$$y_i$$$, $$$a_i$$$ the tuples $$$f^{(k)}$$$ starting from some index will repeat tuples with smaller indices. Calculate the maximum number of different tuples (from all $$$f^{(k)}$$$ for $$$k \ge 0$$$) that can be produced by this generator, if $$$x_i$$$, $$$a_i$$$, $$$b_i$$$ are integers in the range $$$[0, p_i - 1]$$$ and can be chosen arbitrary. The answer can be large, so print the remainder it gives when divided by $$$10^9 + 7$$$",['number theory']1167"You are given two integers $$$l$$$ and $$$r$$$ in binary representation. Let $$$g(x, y)$$$ be equal to the bitwise XOR of all integers from $$$x$$$ to $$$y$$$ inclusive (that is $$$x \oplus (x+1) \oplus \dots \oplus (y-1) \oplus y$$$). Let's define $$$f(l, r)$$$ as the maximum of all values of $$$g(x, y)$$$ satisfying $$$l \le x \le y \le r$$$.Output $$$f(l, r)$$$.","['math', 'strings']"1168"Roma (a popular Russian name that means 'Roman') loves the Little Lvov Elephant's lucky numbers.Let us remind you that lucky numbers are positive integers whose decimal representation only contains lucky digits 4 and 7. For example, numbers 47, 744, 4 are lucky and 5, 17, 467 are not.Roma's got n positive integers. He wonders, how many of those integers have not more than k lucky digits? Help him, write the program that solves the problem.",[]1169"In BerSoft $$$n$$$ programmers work, the programmer $$$i$$$ is characterized by a skill $$$r_i$$$.A programmer $$$a$$$ can be a mentor of a programmer $$$b$$$ if and only if the skill of the programmer $$$a$$$ is strictly greater than the skill of the programmer $$$b$$$ $$$(r_a > r_b)$$$ and programmers $$$a$$$ and $$$b$$$ are not in a quarrel.You are given the skills of each programmers and a list of $$$k$$$ pairs of the programmers, which are in a quarrel (pairs are unordered). For each programmer $$$i$$$, find the number of programmers, for which the programmer $$$i$$$ can be a mentor.",[]1170"Some people leave the lights at their workplaces on when they leave that is a waste of resources. As a hausmeister of DHBW, Sagheer waits till all students and professors leave the university building, then goes and turns all the lights off.The building consists of n floors with stairs at the left and the right sides. Each floor has m rooms on the same line with a corridor that connects the left and right stairs passing by all the rooms. In other words, the building can be represented as a rectangle with n rows and m + 2 columns, where the first and the last columns represent the stairs, and the m columns in the middle represent rooms.Sagheer is standing at the ground floor at the left stairs. He wants to turn all the lights off in such a way that he will not go upstairs until all lights in the floor he is standing at are off. Of course, Sagheer must visit a room to turn the light there off. It takes one minute for Sagheer to go to the next floor using stairs or to move from the current room/stairs to a neighboring room/stairs on the same floor. It takes no time for him to switch the light off in the room he is currently standing in. Help Sagheer find the minimum total time to turn off all the lights.Note that Sagheer does not have to go back to his starting position, and he does not have to visit rooms where the light is already switched off.",[]1171"This is an interactive problem. Remember to flush your output while communicating with the testing program. You may use fflush(stdout) in C++, system.out.flush() in Java, stdout.flush() in Python or flush(output) in Pascal to flush the output. If you use some other programming language, consult its documentation. You may also refer to the guide on interactive problems: https://codeforces.com/blog/entry/45307.The jury picked an integer $$$x$$$ not less than $$$0$$$ and not greater than $$$2^{14} - 1$$$. You have to guess this integer.To do so, you may ask no more than $$$2$$$ queries. Each query should consist of $$$100$$$ integer numbers $$$a_1$$$, $$$a_2$$$, ..., $$$a_{100}$$$ (each integer should be not less than $$$0$$$ and not greater than $$$2^{14} - 1$$$). In response to your query, the jury will pick one integer $$$i$$$ ($$$1 \le i \le 100$$$) and tell you the value of $$$a_i \oplus x$$$ (the bitwise XOR of $$$a_i$$$ and $$$x$$$). There is an additional constraint on the queries: all $$$200$$$ integers you use in the queries should be distinct.It is guaranteed that the value of $$$x$$$ is fixed beforehand in each test, but the choice of $$$i$$$ in every query may depend on the integers you send.",['math']1172"Jeel and Ashish play a game on an $$$n \times m$$$ matrix. The rows are numbered $$$1$$$ to $$$n$$$ from top to bottom and the columns are numbered $$$1$$$ to $$$m$$$ from left to right. They play turn by turn. Ashish goes first.Initially, each cell of the matrix contains a non-negative integer. Each turn, a player must perform all of the following actions in order.   Choose a starting cell $$$(r_1, c_1)$$$ with non-zero value.  Choose a finishing cell $$$(r_2, c_2)$$$ such that $$$r_1 \leq r_2$$$ and $$$c_1 \leq c_2$$$.  Decrease the value of the starting cell by some positive non-zero integer.  Pick any of the shortest paths between the two cells and either increase, decrease or leave the values of cells on this path unchanged. Note that:   a shortest path is one that passes through the least number of cells;  all cells on this path excluding the starting cell, but the finishing cell may be modified;  the resulting value of each cell must be a non-negative integer;  the cells are modified independently and not necessarily by the same value.  If the starting and ending cells are the same, then as per the rules, the value of the cell is decreased. No other operations are performed.The game ends when all the values become zero. The player who is unable to make a move loses. It can be shown that the game will end in a finite number of moves if both players play optimally.Given the initial matrix, if both players play optimally, can you predict who will win?",['games']1173"Little Robber Girl likes to scare animals in her zoo for fun. She decided to arrange the animals in a row in the order of non-decreasing height. However, the animals were so scared that they couldn't stay in the right places.The robber girl was angry at first, but then she decided to arrange the animals herself. She repeatedly names numbers l and r such that r - l + 1 is even. After that animals that occupy positions between l and r inclusively are rearranged as follows: the animal at position l swaps places with the animal at position l + 1, the animal l + 2 swaps with the animal l + 3, ..., finally, the animal at position r - 1 swaps with the animal r.Help the robber girl to arrange the animals in the order of non-decreasing height. You should name at most 20 000 segments, since otherwise the robber girl will become bored and will start scaring the animals again.",[]1174"PolandBall lives in a forest with his family. There are some trees in the forest. Trees are undirected acyclic graphs with k vertices and k - 1 edges, where k is some integer. Note that one vertex is a valid tree.There is exactly one relative living in each vertex of each tree, they have unique ids from 1 to n. For each Ball i we know the id of its most distant relative living on the same tree. If there are several such vertices, we only know the value of the one with smallest id among those.How many trees are there in the forest?","['graphs', 'trees']"1175"You have a playlist consisting of $$$n$$$ songs. The $$$i$$$-th song is characterized by two numbers $$$t_i$$$ and $$$b_i$$$ — its length and beauty respectively. The pleasure of listening to set of songs is equal to the total length of the songs in the set multiplied by the minimum beauty among them. For example, the pleasure of listening to a set of $$$3$$$ songs having lengths $$$[5, 7, 4]$$$ and beauty values $$$[11, 14, 6]$$$ is equal to $$$(5 + 7 + 4) \cdot 6 = 96$$$.You need to choose at most $$$k$$$ songs from your playlist, so the pleasure of listening to the set of these songs them is maximum possible.",[]1176"Today at the lesson of mathematics, Petya learns about the digital root.The digital root of a non-negative integer is the single digit value obtained by an iterative process of summing digits, on each iteration using the result from the previous iteration to compute a digit sum. The process continues until a single-digit number is reached. Let's denote the digital root of $$$x$$$ as $$$S(x)$$$. Then $$$S(5)=5$$$, $$$S(38)=S(3+8=11)=S(1+1=2)=2$$$, $$$S(10)=S(1+0=1)=1$$$.As a homework Petya got $$$n$$$ tasks of the form: find $$$k$$$-th positive number whose digital root is $$$x$$$.Petya has already solved all the problems, but he doesn't know if it's right. Your task is to solve all $$$n$$$ tasks from Petya's homework.","['math', 'number theory']"1177"This is an easier version of the next problem. The difference is only in constraints.You are given a rectangular $$$n \times m$$$ matrix $$$a$$$. In one move you can choose any column and cyclically shift elements in this column. You can perform this operation as many times as you want (possibly zero). You can perform this operation to a column multiple times.After you are done with cyclical shifts, you compute for every row the maximal value in it. Suppose that for $$$i$$$-th row it is equal $$$r_i$$$. What is the maximal possible value of $$$r_1+r_2+\ldots+r_n$$$?",[]1178"As you know, Hogwarts has four houses: Gryffindor, Hufflepuff, Ravenclaw and Slytherin. The sorting of the first-years into houses is done by the Sorting Hat. The pupils are called one by one in the alphabetical order, each of them should put a hat on his head and, after some thought, the hat solemnly announces the name of the house the student should enter.At that the Hat is believed to base its considerations on the student's personal qualities: it sends the brave and noble ones to Gryffindor, the smart and shrewd ones — to Ravenclaw, the persistent and honest ones — to Hufflepuff and the clever and cunning ones — to Slytherin. However, a first year student Hermione Granger got very concerned about the forthcoming sorting. She studied all the literature on the Sorting Hat and came to the conclusion that it is much simpler than that. If the relatives of the student have already studied at Hogwarts, the hat puts the student to the same house, where his family used to study. In controversial situations, when the relatives studied in different houses or when they were all Muggles like Hermione's parents, then the Hat sorts the student to the house, to which the least number of first years has been sent at that moment. If there are several such houses, the choice is given to the student himself. Then the student can choose any of the houses, to which the least number of first years has been sent so far. Hermione has already asked the students that are on the list before her about their relatives. Now she and her new friends Harry Potter and Ron Weasley want to find out into what house the Hat will put Hermione.",[]1179"A correct expression of the form a+b=c was written; a, b and c are non-negative integers without leading zeros. In this expression, the plus and equally signs were lost. The task is to restore the expression. In other words, one character '+' and one character '=' should be inserted into given sequence of digits so that:   character'+' is placed on the left of character '=',  characters '+' and '=' split the sequence into three non-empty subsequences consisting of digits (let's call the left part a, the middle part — b and the right part — c),  all the three parts a, b and c do not contain leading zeros,  it is true that a+b=c. It is guaranteed that in given tests answer always exists.",['math']1180"Welcome to another task about breaking the code lock! Explorers Whitfield and Martin came across an unusual safe, inside of which, according to rumors, there are untold riches, among which one can find the solution of the problem of discrete logarithm!Of course, there is a code lock is installed on the safe. The lock has a screen that displays a string of n lowercase Latin letters. Initially, the screen displays string s. Whitfield and Martin found out that the safe will open when string t will be displayed on the screen.The string on the screen can be changed using the operation «shift x». In order to apply this operation, explorers choose an integer x from 0 to n inclusive. After that, the current string p = αβ changes to βRα, where the length of β is x, and the length of α is n - x. In other words, the suffix of the length x of string p is reversed and moved to the beginning of the string. For example, after the operation «shift 4» the string «abcacb» will be changed with string «bcacab », since α = ab, β = cacb, βR = bcac.Explorers are afraid that if they apply too many operations «shift», the lock will be locked forever. They ask you to find a way to get the string t on the screen, using no more than 6100 operations.",['strings']1181"Vanya smashes potato in a vertical food processor. At each moment of time the height of the potato in the processor doesn't exceed h and the processor smashes k centimeters of potato each second. If there are less than k centimeters remaining, than during this second processor smashes all the remaining potato.Vanya has n pieces of potato, the height of the i-th piece is equal to ai. He puts them in the food processor one by one starting from the piece number 1 and finishing with piece number n. Formally, each second the following happens:  If there is at least one piece of potato remaining, Vanya puts them in the processor one by one, until there is not enough space for the next piece.  Processor smashes k centimeters of potato (or just everything that is inside). Provided the information about the parameter of the food processor and the size of each potato in a row, compute how long will it take for all the potato to become smashed.",['math']1182"Alice and Bob are going to celebrate Christmas by playing a game with a tree of presents. The tree has $$$n$$$ nodes (numbered $$$1$$$ to $$$n$$$, with some node $$$r$$$ as its root). There are $$$a_i$$$ presents are hanging from the $$$i$$$-th node.Before beginning the game, a special integer $$$k$$$ is chosen. The game proceeds as follows: Alice begins the game, with moves alternating each turn; in any move, the current player may choose some node (for example, $$$i$$$) which has depth at least $$$k$$$. Then, the player picks some positive number of presents hanging from that node, let's call it $$$m$$$ $$$(1 \le m \le a_i)$$$; the player then places these $$$m$$$ presents on the $$$k$$$-th ancestor (let's call it $$$j$$$) of the $$$i$$$-th node (the $$$k$$$-th ancestor of vertex $$$i$$$ is a vertex $$$j$$$ such that $$$i$$$ is a descendant of $$$j$$$, and the difference between the depth of $$$j$$$ and the depth of $$$i$$$ is exactly $$$k$$$). Now, the number of presents of the $$$i$$$-th node $$$(a_i)$$$ is decreased by $$$m$$$, and, correspondingly, $$$a_j$$$ is increased by $$$m$$$; Alice and Bob both play optimally. The player unable to make a move loses the game.For each possible root of the tree, find who among Alice or Bob wins the game.Note: The depth of a node $$$i$$$ in a tree with root $$$r$$$ is defined as the number of edges on the simple path from node $$$r$$$ to node $$$i$$$. The depth of root $$$r$$$ itself is zero.","['math', 'trees', 'games']"1183"There are n employees in Alternative Cake Manufacturing (ACM). They are now voting on some very important question and the leading world media are trying to predict the outcome of the vote.Each of the employees belongs to one of two fractions: depublicans or remocrats, and these two fractions have opposite opinions on what should be the outcome of the vote. The voting procedure is rather complicated:   Each of n employees makes a statement. They make statements one by one starting from employees 1 and finishing with employee n. If at the moment when it's time for the i-th employee to make a statement he no longer has the right to vote, he just skips his turn (and no longer takes part in this voting).  When employee makes a statement, he can do nothing or declare that one of the other employees no longer has a right to vote. It's allowed to deny from voting people who already made the statement or people who are only waiting to do so. If someone is denied from voting he no longer participates in the voting till the very end.  When all employees are done with their statements, the procedure repeats: again, each employees starting from 1 and finishing with n who are still eligible to vote make their statements.  The process repeats until there is only one employee eligible to vote remaining and he determines the outcome of the whole voting. Of course, he votes for the decision suitable for his fraction. You know the order employees are going to vote and that they behave optimal (and they also know the order and who belongs to which fraction). Predict the outcome of the vote.",[]1184"Fishingprince is playing with an array $$$[a_1,a_2,\dots,a_n]$$$. He also has a magic number $$$m$$$.He can do the following two operations on it:  Select $$$1\le i\le n$$$ such that $$$a_i$$$ is divisible by $$$m$$$ (that is, there exists an integer $$$t$$$ such that $$$m \cdot t = a_i$$$). Replace $$$a_i$$$ with $$$m$$$ copies of $$$\frac{a_i}{m}$$$. The order of the other elements doesn't change. For example, when $$$m=2$$$ and $$$a=[2,3]$$$ and $$$i=1$$$, $$$a$$$ changes into $$$[1,1,3]$$$.  Select $$$1\le i\le n-m+1$$$ such that $$$a_i=a_{i+1}=\dots=a_{i+m-1}$$$. Replace these $$$m$$$ elements with a single $$$m \cdot a_i$$$. The order of the other elements doesn't change. For example, when $$$m=2$$$ and $$$a=[3,2,2,3]$$$ and $$$i=2$$$, $$$a$$$ changes into $$$[3,4,3]$$$. Note that the array length might change during the process. The value of $$$n$$$ above is defined as the current length of the array (might differ from the $$$n$$$ in the input).Fishingprince has another array $$$[b_1,b_2,\dots,b_k]$$$. Please determine if he can turn $$$a$$$ into $$$b$$$ using any number (possibly zero) of operations.",['math']1185"You are given a positive integer $$$n$$$. Let's call some positive integer $$$a$$$ without leading zeroes palindromic if it remains the same after reversing the order of its digits. Find the number of distinct ways to express $$$n$$$ as a sum of positive palindromic integers. Two ways are considered different if the frequency of at least one palindromic integer is different in them. For example, $$$5=4+1$$$ and $$$5=3+1+1$$$ are considered different but $$$5=3+1+1$$$ and $$$5=1+3+1$$$ are considered the same. Formally, you need to find the number of distinct multisets of positive palindromic integers the sum of which is equal to $$$n$$$.Since the answer can be quite large, print it modulo $$$10^9+7$$$.","['math', 'number theory']"1186"Analyzing the mistakes people make while typing search queries is a complex and an interesting work. As there is no guaranteed way to determine what the user originally meant by typing some query, we have to use different sorts of heuristics.Polycarp needed to write a code that could, given two words, check whether they could have been obtained from the same word as a result of typos. Polycarpus suggested that the most common typo is skipping exactly one letter as you type a word.Implement a program that can, given two distinct words S and T of the same length n determine how many words W of length n + 1 are there with such property that you can transform W into both S, and T by deleting exactly one character. Words S and T consist of lowercase English letters. Word W also should consist of lowercase English letters.",['strings']1187"There are some websites that are accessible through several different addresses. For example, for a long time Codeforces was accessible with two hostnames codeforces.com and codeforces.ru.You are given a list of page addresses being queried. For simplicity we consider all addresses to have the form http://<hostname>[/<path>], where:  <hostname> — server name (consists of words and maybe some dots separating them),  /<path> — optional part, where <path> consists of words separated by slashes. We consider two <hostname> to correspond to one website if for each query to the first <hostname> there will be exactly the same query to the second one and vice versa — for each query to the second <hostname> there will be the same query to the first one. Take a look at the samples for further clarifications.Your goal is to determine the groups of server names that correspond to one website. Ignore groups consisting of the only server name.Please note, that according to the above definition queries http://<hostname> and http://<hostname>/ are different.",['strings']1188"Evlampiy was gifted a rooted tree. The vertices of the tree are numbered from $$$1$$$ to $$$n$$$. Each of its vertices also has an integer $$$a_i$$$ written on it. For each vertex $$$i$$$, Evlampiy calculated $$$c_i$$$ — the number of vertices $$$j$$$ in the subtree of vertex $$$i$$$, such that $$$a_j < a_i$$$. Illustration for the second example, the first integer is $$$a_i$$$ and the integer in parentheses is $$$c_i$$$After the new year, Evlampiy could not remember what his gift was! He remembers the tree and the values of $$$c_i$$$, but he completely forgot which integers $$$a_i$$$ were written on the vertices.Help him to restore initial integers!","['graphs', 'trees']"1189"Polycarp wants to cook a soup. To do it, he needs to buy exactly $$$n$$$ liters of water.There are only two types of water bottles in the nearby shop — $$$1$$$-liter bottles and $$$2$$$-liter bottles. There are infinitely many bottles of these two types in the shop.The bottle of the first type costs $$$a$$$ burles and the bottle of the second type costs $$$b$$$ burles correspondingly.Polycarp wants to spend as few money as possible. Your task is to find the minimum amount of money (in burles) Polycarp needs to buy exactly $$$n$$$ liters of water in the nearby shop if the bottle of the first type costs $$$a$$$ burles and the bottle of the second type costs $$$b$$$ burles. You also have to answer $$$q$$$ independent queries.",['math']1190"Creatnx has $$$n$$$ mirrors, numbered from $$$1$$$ to $$$n$$$. Every day, Creatnx asks exactly one mirror ""Am I beautiful?"". The $$$i$$$-th mirror will tell Creatnx that he is beautiful with probability $$$\frac{p_i}{100}$$$ for all $$$1 \le i \le n$$$.Some mirrors are called checkpoints. Initially, only the $$$1$$$st mirror is a checkpoint. It remains a checkpoint all the time.Creatnx asks the mirrors one by one, starting from the $$$1$$$-st mirror. Every day, if he asks $$$i$$$-th mirror, there are two possibilities:  The $$$i$$$-th mirror tells Creatnx that he is beautiful. In this case, if $$$i = n$$$ Creatnx will stop and become happy, otherwise he will continue asking the $$$i+1$$$-th mirror next day;  In the other case, Creatnx will feel upset. The next day, Creatnx will start asking from the checkpoint with a maximal number that is less or equal to $$$i$$$. There are some changes occur over time: some mirrors become new checkpoints and some mirrors are no longer checkpoints. You are given $$$q$$$ queries, each query is represented by an integer $$$u$$$: If the $$$u$$$-th mirror isn't a checkpoint then we set it as a checkpoint. Otherwise, the $$$u$$$-th mirror is no longer a checkpoint.After each query, you need to calculate the expected number of days until Creatnx becomes happy.Each of this numbers should be found by modulo $$$998244353$$$. Formally, let $$$M = 998244353$$$. It can be shown that the answer can be expressed as an irreducible fraction $$$\frac{p}{q}$$$, where $$$p$$$ and $$$q$$$ are integers and $$$q \not \equiv 0 \pmod{M}$$$. Output the integer equal to $$$p \cdot q^{-1} \bmod M$$$. In other words, output such an integer $$$x$$$ that $$$0 \le x < M$$$ and $$$x \cdot q \equiv p \pmod{M}$$$.",['probabilities']1191"Lee is going to fashionably decorate his house for a party, using some regular convex polygons...Lee thinks a regular $$$n$$$-sided (convex) polygon is beautiful if and only if he can rotate it in such a way that at least one of its edges is parallel to the $$$OX$$$-axis and at least one of its edges is parallel to the $$$OY$$$-axis at the same time.Recall that a regular $$$n$$$-sided polygon is a convex polygon with $$$n$$$ vertices such that all the edges and angles are equal.Now he is shopping: the market has $$$t$$$ regular polygons. For each of them print YES if it is beautiful and NO otherwise.","['math', 'geometry']"1192"Koa the Koala has a binary string $$$s$$$ of length $$$n$$$. Koa can perform no more than $$$n-1$$$ (possibly zero) operations of the following form:In one operation Koa selects positions $$$i$$$ and $$$i+1$$$ for some $$$i$$$ with $$$1 \le i < |s|$$$ and sets $$$s_i$$$ to $$$max(s_i, s_{i+1})$$$. Then Koa deletes position $$$i+1$$$ from $$$s$$$ (after the removal, the remaining parts are concatenated).Note that after every operation the length of $$$s$$$ decreases by $$$1$$$.How many different binary strings can Koa obtain by doing no more than $$$n-1$$$ (possibly zero) operations modulo $$$10^9+7$$$ ($$$1000000007$$$)?",[]1193"There is a chip on the coordinate line. Initially, the chip is located at the point $$$0$$$. You can perform any number of moves; each move increases the coordinate of the chip by some positive integer (which is called the length of the move). The length of the first move you make should be divisible by $$$k$$$, the length of the second move — by $$$k+1$$$, the third — by $$$k+2$$$, and so on.For example, if $$$k=2$$$, then the sequence of moves may look like this: $$$0 \rightarrow 4 \rightarrow 7 \rightarrow 19 \rightarrow 44$$$, because $$$4 - 0 = 4$$$ is divisible by $$$2 = k$$$, $$$7 - 4 = 3$$$ is divisible by $$$3 = k + 1$$$, $$$19 - 7 = 12$$$ is divisible by $$$4 = k + 2$$$, $$$44 - 19 = 25$$$ is divisible by $$$5 = k + 3$$$.You are given two positive integers $$$n$$$ and $$$k$$$. Your task is to count the number of ways to reach the point $$$x$$$, starting from $$$0$$$, for every $$$x \in [1, n]$$$. The number of ways can be very large, so print it modulo $$$998244353$$$. Two ways are considered different if they differ as sets of visited positions.",['math']1194"Ori and Sein have overcome many difficult challenges. They finally lit the Shrouded Lantern and found Gumon Seal, the key to the Forlorn Ruins. When they tried to open the door to the ruins... nothing happened.Ori was very surprised, but Sein gave the explanation quickly: clever Gumon decided to make an additional defence for the door.There are $$$n$$$ lamps with Spirit Tree's light. Sein knows the time of turning on and off for the $$$i$$$-th lamp — $$$l_i$$$ and $$$r_i$$$ respectively. To open the door you have to choose $$$k$$$ lamps in such a way that there will be a moment of time when they all will be turned on.While Sein decides which of the $$$k$$$ lamps to pick, Ori is interested: how many ways there are to pick such $$$k$$$ lamps that the door will open? It may happen that Sein may be wrong and there are no such $$$k$$$ lamps. The answer might be large, so print it modulo $$$998\,244\,353$$$.",[]1195"Ivan decided to prepare for the test on solving integer equations. He noticed that all tasks in the test have the following form:  You are given two positive integers $$$u$$$ and $$$v$$$, find any pair of integers (not necessarily positive) $$$x$$$, $$$y$$$, such that: $$$$$$\frac{x}{u} + \frac{y}{v} = \frac{x + y}{u + v}.$$$$$$  The solution $$$x = 0$$$, $$$y = 0$$$ is forbidden, so you should find any solution with $$$(x, y) \neq (0, 0)$$$. Please help Ivan to solve some equations of this form.",['math']1196"The clique problem is one of the most well-known NP-complete problems. Under some simplification it can be formulated as follows. Consider an undirected graph G. It is required to find a subset of vertices C of the maximum size such that any two of them are connected by an edge in graph G. Sounds simple, doesn't it? Nobody yet knows an algorithm that finds a solution to this problem in polynomial time of the size of the graph. However, as with many other NP-complete problems, the clique problem is easier if you consider a specific type of a graph.Consider n distinct points on a line. Let the i-th point have the coordinate xi and weight wi. Let's form graph G, whose vertices are these points and edges connect exactly the pairs of points (i, j), such that the distance between them is not less than the sum of their weights, or more formally: |xi - xj| ≥ wi + wj.Find the size of the maximum clique in such graph.",[]1197"You are given a broken clock. You know, that it is supposed to show time in 12- or 24-hours HH:MM format. In 12-hours format hours change from 1 to 12, while in 24-hours it changes from 0 to 23. In both formats minutes change from 0 to 59.You are given a time in format HH:MM that is currently displayed on the broken clock. Your goal is to change minimum number of digits in order to make clocks display the correct time in the given format.For example, if 00:99 is displayed, it is enough to replace the second 9 with 3 in order to get 00:39 that is a correct time in 24-hours format. However, to make 00:99 correct in 12-hours format, one has to change at least two digits. Additionally to the first change one can replace the second 0 with 1 and obtain 01:39.",[]1198"Boboniu likes bit operations. He wants to play a game with you.Boboniu gives you two sequences of non-negative integers $$$a_1,a_2,\ldots,a_n$$$ and $$$b_1,b_2,\ldots,b_m$$$.For each $$$i$$$ ($$$1\le i\le n$$$), you're asked to choose a $$$j$$$ ($$$1\le j\le m$$$) and let $$$c_i=a_i\& b_j$$$, where $$$\&$$$ denotes the bitwise AND operation. Note that you can pick the same $$$j$$$ for different $$$i$$$'s.Find the minimum possible $$$c_1 | c_2 | \ldots | c_n$$$, where $$$|$$$ denotes the bitwise OR operation.",[]1199"Consider the following problem: given an array $$$a$$$ containing $$$n$$$ integers (indexed from $$$0$$$ to $$$n-1$$$), find $$$\max\limits_{0 \leq l \leq r \leq n-1} \sum\limits_{l \leq i \leq r} (r-l+1) \cdot a_i$$$. In this problem, $$$1 \leq n \leq 2\,000$$$ and $$$|a_i| \leq 10^6$$$.In an attempt to solve the problem described, Alice quickly came up with a blazing-fast greedy algorithm and coded it. Her implementation in pseudocode is as follows:function find_answer(n, a)    # Assumes n is an integer between 1 and 2000, inclusive    # Assumes a is a list containing n integers: a[0], a[1], ..., a[n-1]    res = 0    cur = 0    k = -1    for i = 0 to i = n-1        cur = cur + a[i]        if cur < 0            cur = 0            k = i        res = max(res, (i-k)*cur)    return resAlso, as you can see, Alice's idea is not entirely correct. For example, suppose $$$n = 4$$$ and $$$a = [6, -8, 7, -42]$$$. Then, find_answer(n, a) would return $$$7$$$, but the correct answer is $$$3 \cdot (6-8+7) = 15$$$.You told Alice that her solution is incorrect, but she did not believe what you said.Given an integer $$$k$$$, you are to find any sequence $$$a$$$ of $$$n$$$ integers such that the correct answer and the answer produced by Alice's algorithm differ by exactly $$$k$$$. Note that although the choice of $$$n$$$ and the content of the sequence is yours, you must still follow the constraints earlier given: that $$$1 \leq n \leq 2\,000$$$ and that the absolute value of each element does not exceed $$$10^6$$$. If there is no such sequence, determine so.",[]1200"Yura has been walking for some time already and is planning to return home. He needs to get home as fast as possible. To do this, Yura can use the instant-movement locations around the city.Let's represent the city as an area of $$$n \times n$$$ square blocks. Yura needs to move from the block with coordinates $$$(s_x,s_y)$$$ to the block with coordinates $$$(f_x,f_y)$$$. In one minute Yura can move to any neighboring by side block; in other words, he can move in four directions. Also, there are $$$m$$$ instant-movement locations in the city. Their coordinates are known to you and Yura. Yura can move to an instant-movement location in no time if he is located in a block with the same coordinate $$$x$$$ or with the same coordinate $$$y$$$ as the location.Help Yura to find the smallest time needed to get home.",['graphs']

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