u014135990的专栏

ing 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

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".

at consists of n × m unit squares. He wants to cut this bar exactly k times. Each cut must meet the following requirements:each cut should be straight (horizontal or vertical);each cut should go along edges of unit squares (it is prohibited to divide

also is very smart.While some of us were learning the multiplication table, Bizon the Champion had fun in his own manner. Bizon the Champion painted ann × m multiplication table, where the element on the intersection of the i-th row and j-th column equal

is very hardworking.Bizon the Champion decided to paint his old fence his favorite color, orange. The fence is represented as n vertical planks, put in a row. Adjacent planks have no gap between them. The planks are numbered from the left to the right st

a pawn. It has only two variants of moving: upwards and leftwards or upwards and rightwards. The pawn can choose from which square of the lowest row it can start its journey. On each square lay from 0 to 9 peas. The pawn wants to reach the uppermost row ha

bout the Codeforces site, which is rapidly getting more and more popular among the brightest minds of the humanity, who are using it for training and competing. Recently Copa understood that to conquer the world he needs to organize the world Codeforces to

e much more than the Persians but Shapur is ready to defeat them. He says: "A lion is never afraid of a hundred sheep".Nevertheless Shapur has to find weaknesses in the Roman army to defeat them. So he gives the army a weakness number.In Shap

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 collecte

rs a1, a2, ..., an. You are allowed to perform two operations on this array:Calculate the sum of current array elements on the segment [l, r], that is, count value al + al + 1 + ... + ar.Apply the xor operation with a given number x to each array elem

s very much. You can see some of them below.Imagine you are given a sequence of positive integer numbers p1, p2, ..., pn. Lets write down some magic formulas:Here, "mod" means the operation of taking the residue after dividing.The expres

integers a1, a2, ..., an. Ivan knows that the array is sorted in the non-decreasing order.Ivan wrote out integers 2a1, 2a2, ..., 2an on a piece of paper. Now he wonders, what minimum number of integers of form 2b (b ≥ 0)need to be added to the piece of

ored, he comes up with games. One long winter evening he came up with a game and decided to play it.Given a sequence a consisting of n integers. The player can make several steps. In a single step he can choose an element of the sequence (let's denote it

s p1,   p2,   ...,   pn, consisting of n distinct positive integers not larger than n. We'll denote as n the length of permutation p1,   p2,   ...,   pn.Your task is to find such permutation p of length n, that the group of numbers |p1 - p2|, |p2 - p3|, 

Now it's Marmot's dinner time and, as we all know, Marmot eats flowers. At every dinner he eats some red and white flowers. Therefore a dinner can be represented as a sequence of several flowers, some of them white and some of them red.But, for a dinner

recently he has found it too easy. So he invented a new game.Initially you have a sequence of n integers: 1, 2, ..., n. In a single step, you can pick two of them, let's denote them a and b, erase them from the sequence, and append to the sequence either

(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 

owers from the garden. There are n flowers in the garden and the i-th of them has a beauty number bi. Parmida is a very strange girl so she doesn't want to have the two most beautiful flowers necessarily. She wants to have those pairs of flowers that their

girl called Parmida since one year ago...Today, Pashmak set up a meeting with his partner in a romantic garden. Unfortunately, Pashmak has forgotten where the garden is. But he remembers that the garden looks like a square with sides parallel to the coo

with it.He has a chessboard of n rows and m columns. Some cells of the chessboard are bad, others are good. For every good cell, DZY wants to put a chessman on it. Each chessman is either white or black. After putting all chessmen, DZY wants that no two

all the consecutive equal characters, the resulting string is palindrome. For example, "aabba" is good, because after the merging step it will become "aba".Given a string, you have to find two values:the number of good substrings o

ournament. Three teams are participating in it. Currently k games had already been played.You are an avid football fan, but recently you missed the whole k games. Fortunately, you remember a guess of your friend for these kgames. Your friend did not tell

udo 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,

is fed up with common dominoes and he uses the dominoes of different heights. He put ndominoes on the table along one axis, going from left to right. Every domino stands perpendicular to that axis so that the axis passes through the center of its base. The

in 2214 will be the participants who win in one of the elimination rounds.The elimination rounds are divided into main and additional. Each of the main elimination rounds consists of c problems, the winners of the round are the first n people in the rati

, in which players control the footballers' figures mounted on rods by using bars to get the ball into the opponent's goal. When playing two on two, one player of each team controls the goalkeeper and the full-backs (plays defence), the other player contro

ress. Now we are even allowed to use decimal notation instead of counting sticks. After the test the teacher promised to show us a "very beautiful number". But the problem is, he's left his paper with the number in the teachers' office.The teac

ey have the same size and weight, but they might have different strength. The i-th box can hold at most xi boxes on its top (we'll call xi the strength of the box).Since all the boxes have the same size, Ciel cannot put more than one box directly on the

the digital clock. Besides, George knows that he has slept for time t.Help George! Write a program that will, given time s and t, determine the time p when George went to bed. Note that George could have gone to bed yesterday relatively to the current t

a structures and faced the following problem.You are given a sequence of integers x1, x2, ..., xn of length n and m queries, each of them is characterized by two integers li, ri. Let's introduce f(p) to represent the number of such indexes k, that xk is

(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 substr

ent. 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

hey've got a competition.Arthur took a group of four integers a, b, w, x (0 ≤ b < w, 0 < x < w) and Alexander took integer с. Arthur and Alexander use distinct approaches to number bustings. Alexander is just a regular guy. Each seco

especially likes stairs.Sequence a1, a2, ..., a|a| (|a| is the length of the sequence) is stairs if there is such index i (1 ≤ i ≤ |a|), that the following condition is met:a1 < a2 < ... < ai - 1 < ai > ai + 1 &g

In order to do this, he wants to sort n arrays simultaneously, each array consisting of mintegers.Iahub can choose a pair of distinct indices i and j (1 ≤ i, j ≤ m, i ≠ j). Then in each array the values at positions i and j are swapped only if the value

ite (let's call it X) has come up with a New Year adventure. Specifically, they decided to give ratings to all visitors.There are n users on the site, for each user we know the rating value he wants to get as a New Year Present. We know that user i wants

ons. Especially in programming contests. Today he has participated in the contest with his team, consisting of n students (including Valera). This contest was an individual competition, so each student in the team solved problems individually.After the c

s. Our box with Domino was empty, so we decided to borrow the teacher's dominoes.The teacher responded instantly at our request. He put nm dominoes on the table as an n × 2m rectangle so that each of the n rows contained m dominoes arranged horizontally.

ed 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 s