Please solve the programming task below using a self-contained code snippet in a markdown code block.

There is an undirected tree with n nodes labeled from 0 to n - 1. You are given the integer n and a 2D integer array edges of length n - 1, where edges[i] = [ai, bi] indicates that there is an edge between nodes ai and bi in the tree. The root of the tree is the node labeled 0.
Each node has an associated value. You are given an array values of length n, where values[i] is the value of the ith node.
Select any two non-overlapping subtrees. Your score is the bitwise XOR of the sum of the values within those subtrees.
Return the maximum possible score you can achieve. If it is impossible to find two nonoverlapping subtrees, return 0.
Note that:

The subtree of a node is the tree consisting of that node and all of its descendants.
Two subtrees are non-overlapping if they do not share any common node.

 
Please complete the following python code precisely:
```python
class Solution:
    def maxXor(self, n: int, edges: List[List[int]], values: List[int]) -> int:
```