摘要：
Petr stands in line of n people, but he doesn't know exactly which position he occupies. He can say that there are no less than a people standing in f 阅读全文
摘要：
You are given a broken clock. You know, that it is supposed to show time in 12- or 24-hours HH:MM format. In 12-hours format hours change from 1 to 12 阅读全文