Tree Diameter

You are given an unweighted tree with n nodes labeled 1 to n, described by an array edges of its n - 1 undirected edges, where edges[i] = [a, b].

The diameter of the tree is the maximum number of edges on a path between any two nodes.

Return the diameter.

Examples

Example 1

Input: n = 5, edges = [[1,2],[1,3],[3,4],[3,5]]
Output: 3
Explanation: The path 2 - 1 - 3 - 4 (or 2 - 1 - 3 - 5) uses 3 edges, and no path is longer.

Example 2

Input: n = 1, edges = []
Output: 0
Explanation: A single node has no path to any other node.