2867. Count Valid Paths in a Tree

There is an undirected tree with n nodes labeled from 1 to n. You are given the integer n and a 2D integer array edges of length n - 1, where edges[i] = [ui, vi] indicates that there is an edge between nodes ui and vi in the tree. Return the number of valid paths in the tree. A path (a, b) is valid if there exists exactly one prime number among the node labels in the path from a to b. Note that