PT07Z - Longest path in a tree


You are given an unweighted, undirected tree. Write a program to output the length of the longest path (from one node to another) in that tree. The length of a path in this case is number of edges we traverse from source to destination.

Input

The first line of the input file contains one integer N --- number of nodes in the tree (0 < N <= 10000). Next N-1 lines contain N-1 edges of that tree --- Each line contains a pair (u, v) means there is an edge between node u and node v (1 <= u, v <= N).

Output

Print the length of the longest path on one line.

Example

Input:
3
1 2
2 3

Output:
2

hide comments
reggaeguitar: 2015-04-07 22:51:13

Although it doesn't imply that the test data is wrong, it does imply that it is incomplete

Mitch Schwartz: 2014-08-20 08:57:07

@Raj Kamal: Getting AC with wrong code does not imply test data is wrong. (Let W = set of cases for which your code produces wrong answer, and let I = set of cases in the actual input. It could be that the intersection of I and W is empty.)

Getting WA with correct code does imply test data is wrong.

This is not a hard concept.

Raj Kamal: 2014-08-19 22:23:29

The test cases are all wrong. As many have already mentioned, I also got AC for the cases mentioned by Pankaj Saini and others, when my solution was actually clearly wrong,

Just by changing the start node that I was using for my algo, I went from getting a WA to an AC

Last edit: 2014-08-19 22:25:15

Added by:Thanh-Vy Hua
Date:2007-03-28
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