摘要：
Description You have a string ss of length nn consisting of only characters > and <. You may do some operations with this string, for each operation y 阅读全文
摘要：
Description Ivan recently bought a detective book. The book is so interesting that each page of this book introduces some sort of a mystery, which wil 阅读全文
摘要：
Description An array of integers p1,p2,…,pnp1,p2,…,pn is called a permutation if it contains each number from 11 to nn exactly once. For example, the 阅读全文