问题 B: The XOR Longest Path

In an edge-weighted tree, the xor-length of a path p is defined as the xor sum of the weights of edges on p:
_xorlength(p)=⊕_e∈pw(e)
⊕ is the xor operator.
We say a path the xor-longest path if it has the largest xor-length. Given an edge-weighted tree with n nodes, can you find the xor-longest path?

The input contains several test cases. The first line of each test case contains an integer n(1≤n≤100000), The following n-1 lines each contains three integers u(0≤u<n),v(0≤v<n),w(0≤w<2³¹), which means there is an edge between node u and v of length w.

For each test case output the xor-length of the xor-longest path.

4
0 1 3
1 2 4
1 3 6

7