摘要：Ignatius is so lucky that he met a Martian yesterday. But he didn't know the language the Martians use. The Martian gives him a history book of Mars a 阅读全文

摘要：Misha hacked the Codeforces site. Then he decided to let all the users change their handles. A user can now change his handle any number of times. But 阅读全文