摘要：
The map of Bertown can be represented as a set of nn intersections, numbered from 11 to nn and connected by mm one-way roads. It is possible to move a 阅读全文
摘要：
You are given a string ss consisting of lowercase Latin letters. Let the length of ss be |s||s| . You may perform several operations on this string. I 阅读全文
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Tanya wants to go on a journey across the cities of Berland. There are nn cities situated along the main railroad line of Berland, and these cities ar 阅读全文
摘要：
Polycarp is preparing the first programming contest for robots. There are nn problems in it, and a lot of robots are going to participate in it. Each 阅读全文