摘要：
Description The little cat is so famous, that many couples tramp over hill and dale to Byteland, and asked the little cat to give names to their newly 阅读全文
摘要：
Description Given two strings a and b we define a*b to be their concatenation. For example, if a = "abc" and b = "def" then a*b = "abcdef". If we thin 阅读全文