摘要：
题目链接：http://codeforces.com/problemset/problem/589/D Welcoming autumn evening is the best for walking along the boulevard and n people decided to do so 阅读全文
摘要：
题目链接：http://codeforces.com/problemset/problem/589/A Polycarp has quite recently learned about email aliases. Of course, he used to suspect that the ca 阅读全文