摘要：
n boys and m girls came to the party. Each boy presented each girl some integer number of sweets (possibly zero). All boys are numbered with integers 阅读全文
摘要：
Let's call an array of non negative integers a1,a2,…,an a k extension for some non negative integer k if for all possible pairs of indices 1≤i,j≤n the 阅读全文
摘要：
A. A pile of stones Vasya has a pile, that consists of some number of stones. n times he either took one stone from the pile or added one stone to the 阅读全文