Contest Clarifications

Problem 1002 请解释样例

orzchimo | 2016-03-26 19:03:36Author

请解释样例

admin | 2016-03-26 19:11:23# 1

。。。

admin | 2016-03-26 19:16:46# 2

样例1：aa，样例2：abba和baab，样例3：a