摘要：
A positive integer aa is given. Baron Munchausen claims that he knows such a positive integer nn that if one multiplies nn by aa, the sum of its digit 阅读全文
摘要：
Bizon the Champion isn't just charming, he also is very smart. While some of us were learning the multiplication table, Bizon the Champion had fun in 阅读全文
摘要：
A string is binary, if it consists only of characters "0" and "1". String v is a substring of string w if it has a non-zero length and can be read sta 阅读全文
摘要：
Berland starts to seize the initiative on the war with Flatland. To drive the enemy from their native land, the berlanders need to know exactly how ma 阅读全文
摘要：
Little Petya likes points a lot. Recently his mom has presented him n points lying on the line OX. Now Petya is wondering in how many ways he can choo 阅读全文