Shandong Normal University ACM-ICPC Association (SAIA) is lack of the history. Jason want himself and YG, GYQ, WHC, TZY, ZXH and YuMa, LeiGe and coach Fang and Li go down in the SDNUAIA annals forever.

In the annals, we can figure out many interesting things. All the things like that, Lei and Yu may both know the theory of game, but it was SYC taught Yu and LBX taught Lei, and ZZK taught LBX, and finally it is a some humbling and numinous power let ZZK and SYC got the theory of game. So we can say that Both Lei and Yu are learn the theory of game from a some humbling and numinous power. We are not concerned with who let the power got that theory.

In the future, you’ll get the annals, find the interesting things I want to know.

The first line contains only one number N(1<=N<=10000). Then the N-1 lines follow, each line contains two integers A and B (1<=A,B<=10000). It indicates that A taught B something useful. The last line contains two integers X and Y(1<=X,Y<=10000), the interesting thing you need to find.

Print Q interesting things you found.

5
2 3
3 4
3 1
1 5
3 5

3