Hello Codeforces !

I can't do this problem. So I copy solution. And I submitted code with some changes, But it get TLE. I submit code without any changes, It get AC. And I delete only commentes in first submission.

First subm.

Second sumb.

And one question. Why?

Hello Codeforces !!!

Does anyone know what have a Codeforces problems like it : 2

All vertices have only one son, except root