摘要：
题目链接 题目 Kefa decided to celebrate his first big salary by going to the restaurant. He lives by an unusual park. The park is a rooted tree consisting o 阅读全文
摘要：
题目链接 题目 Alex doesn't like boredom. That's why whenever he gets bored, he comes up with games. One long winter evening he came up with a game and decid 阅读全文