Hi, CodeForces!

I was solving problem 580C — Kefa and Park where I came up with this code: 300260289. However, it fails on test case 8. If I give it the input:

2 1

1 1

1 2

It outputs 0 but when I provide it "2 1" on the last input it would output 1. Why is that happening?

Any help will be deeply appreciated.

EDIT 1: I solved the problem, the error was I was reading the graph (tree) as directed and I hard coded '0' as the root so whenever '0' is not root it bugs!.