Double Distance Query

You are given an unweighted tree with $N$ nodes (numbered $1$ through $N$). Let's denote the distance between any two nodes $p$ and $q$ by $d(p, q)$. You should answer $Q$ queries. In each query, you are given parameters $a$, $d_a$, $b$, $d_b$, and you should find a node $x$ such that $d(x, a) = d_a$ and $d(x, b) = d_b$, or determine that there is no such node. ### Input - The first line of the