Leaf Counting

Write a function that counts the number of leaf nodes in a binary tree. A leaf is a node that does not have any children. Input format: The first line contains an integer N, the number of nodes in the tree. The next N lines contain three integers each: the node value, the left child value, and the right child value, where -1 indicates that the child does not exist. Output format: Output a single integer representing the number of leaf nodes in the tree. Example: Input: 5 1 2 3 2 4 -1 3 -1 -1 4 -1 -1 5 -1 -1 Output: 3