Intersecting Paths

You are given a tree (a connected undirected graph without cycles) with $N$ vertices numbered $1$ through $N$. For each pair of vertices $u$ and $v$, let's denote the simple path between them by $(u, v)$; the paths are undirected, so $(u, v)$ is the same path as $(v, u)$. You should answer $Q$ queries. In each query, you are given two vertices $u$ and $v$. Then, for each simple path $(a, b)$ in t