Subtree Imbalance Factor

The 'Imbalance Factor' of a node in a BST is the absolute difference between the total number of nodes in its left subtree and the total number of nodes in its right subtree. Given a BST and a target node value X, calculate the Imbalance Factor of the node containing X. If X is not in the tree, return -1. Input: First line contains BST nodes. Second line contains X. Output: The absolute difference in counts or -1. Example: Input: 10 5 15 2 7 12 20 10 Output: 0 Explanation: Node 10 has 3 nodes on the left (5, 2, 7) and 3 on the right (15, 12, 20). |3-3| = 0.