Catcher是MCA国的情报员，他工作时发现敌国会用一些对称的密码进行通信，

比如ABBA，ABA，A，123321等，但是他们有时会在开始或结束时加入一些无关的字符以防别国破解。

比如进行下列变化ABBA->12ABBA,ABA->ABAKK,123321->51233214　。

因为截获的串太长了，而且存在多种可能的情况-Catcher is the the MCA country' s agent, he found that the enemy will work with some symmetric cipher to communicate, such as ABBA, ABA, A, 123321, etc., but they sometimes add some extraneous characters at the beginning or end to prevent other countries crack. For example, following changes ABBA->　12ABBA, ABA->　ABAKK, 123321->　51,233,214. Intercepted by the string is too long, and there are a variety of possible