Hiho! is a serial contests we developed to help programmers improve their skills following some architecture. And for the beginning of this serial, we presents the "String". Dealing with the string is very common when you programming in real world. Although we usually use the standard methods to deal with them, these standard methods contains a lot of brilliant idea inside of it. So we think it's a good idea to hiho some typical string problems to all you, it'll help your programming thinking.

And this problem "Trie graph" is a fantasic way to solve the problem that Mr.Hexie presented at the very beginning in Hiho! Week 3 - "How to search a serial of special words in a long text."!

Ho's hint: It wound be better to finish Week 2 and Week 3 of the hiho! first.

After the end of this contest, we will publish the source code of little HO and all the participants that solved this problem. Wish you learn from each other and make improvement togather!