摘要：
The busses in Berland are equipped with a video surveillance system. The system records information about changes in the number of passengers in a bus 阅读全文
摘要：
You are given a connected undirected graph consisting of nn vertices and mm edges. There are no self-loops or multiple edges in the given graph. You h 阅读全文
摘要：
You are given two strings ss and tt, both consisting of exactly kk lowercase Latin letters, ss is lexicographically less than tt. Let's consider list 阅读全文