The Folder Deduplicator

In a virtual file system, every folder is a node. If two folders have the same set of subfolders (where each subfolder is identical in structure and value), they are considered duplicates. Given a tree where each node has a string label, count how many nodes are the root of a subtree that appears at least once elsewhere in the tree (i.e., there exists another node u such that subtree(u) is identical to subtree(v)). Input Format: - Line 1: N, the number of nodes. - Next N lines: An integer P (parent of node i, -1 for root) and a string S (label of node i). Output Format: - The number of nodes that have at least one identical twin subtree elsewhere. Example: Input: 3 -1 A 0 B 0 B Output: 2 (The two 'B' nodes are identical subtrees.)