You are given a rooted general tree with N nodes, representing a hierarchy of service zones in Uber’s backend system.

Each node i has an integer value A[i], representing the load score of that zone.

For any node v, define score(v) as the bitwise XOR of all load scores in the subtree rooted at v.

Your task is to select two service zones v1 and v2 such that their subtrees are completely independent, meaning they do not share any node.

Return the maximum possible value of:

score(v1) + score(v2)

among all valid pairs of non-overlapping subtrees.