Tree Xor

You are given a **weighted** tree. The distance from node $x$ to node $y$ is calculated as follows: - Let there be $k$ edges in the shortest path from node $x$ to $y$. - Let the weight of these edges, in the same **order** (from $x$ to $y$), be denoted as $e_1, e_2, \ldots, e_k$. - Then, the distance from $x$ to $y$ is denoted as: $d(x, y) = f(e_1, 0) \oplus f(e_2, 1) \oplus f(e_3, 2) \op