Given a tree T with non-negative weight, find the diameter of the tree.
The diameter of a tree is the maximum distance between two nodes in a tree.
n s1 t1 w1 s2 t2 w2 : sn-1 tn-1 wn-1
The first line consists of an integer n which represents the number of nodes in the tree. Every node has a unique ID from 0 to n-1 respectively.
In the following n-1 lines, edges of the tree are given. si and ti represent end-points of the i-th edge (undirected) and wi represents the weight (distance) of the i-th edge.
Print the diameter of the tree in a line.
4 0 1 2 1 2 1 1 3 3
4 0 1 1 1 2 2 2 3 4