Max Depth of Tree with Parent Pointers

You are given a binary tree where each node has a pointer to its parent. Implement a function that calculates the maximum depth of the tree. The depth of a node is defined as the number of edges on the longest downward path from that node to a leaf. Input format: The input starts with an integer n (1 <= n <= 1000), the number of nodes in the tree. Then n lines follow, each containing the value of the node and the value of its parent. If a node does not have a parent (it is the root), the parent value will be -1. Output format: Print a single integer representing the maximum depth of the tree. Example: Input: 5 1 -1 2 1 3 1 4 2 5 2 Output: 2