I hope the program can be funny and useful.

Something about rust:

I love rust programming language very much. And I'm trying to implement something. During the implementation, I found that rust's compiler is very powerful, and it help us catch many error in the run time. So we will not expose too much Runtime Error.

What I learn about is that when we got problem earlier, less time we will waste. In this level, I like it very much. But rust have many concept (Especially something like lifetime, Box). It still makes me confused :( But I think it's very interesting.

Please don't hesitate to tell if you see any bad code or any better way to do something.