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Description   In school of EECS of Peking University, there is a homework for all freshman -- the contest of AI snakes. This contest is ended today. Bacchus has got a very good result, so he decides

Problem DescriptionBeing an ACMer requires knowledge in many fields, because problems in this contest may use physics, biology, and even musicology as background. And now in this problem, you are

Problem DescriptionThe harmonic value of the permutation p1,p2,⋯pn is∑i=1n−1gcd(pi.pi+1)Mr. Frog is wondering about the permutation whose harmonic value is the strictly k-th smallest amo

Problem DescriptionEveryone hates ugly problems.You are given a positive integer. You must represent that number by sum of palindromic numbers.A palindromic number is a positive integer su

There was an epidemic in Monstropolis and all monsters became sick. To recover, all monsters lined up in queue for an appointment to the only doctor in the city.Soon, monsters became hungry and be

Problem DescriptionAs we know, Rikka is poor at math. Yuta is worrying about this situation, so he gives Rikka some math tasks to practice. There is one of them:For an undirected graph G with