The Parental Gap

In a unique ID management system, IDs are stored in a Binary Search Tree (BST). The 'Parental Gap' of a node is defined as the absolute difference between its value and the value of its parent node. Given a sequence of unique integers to build a BST (inserted in the order provided) and a target value, find the Parental Gap of the target node. If the target node is the root of the tree or does not exist in the tree, output -1. Example: Input: 8 3 10 1 6 14; 6 Output: 3 Explanation: 8 is root. 3 is left child of 8. 6 is right child of 3. |6 - 3| = 3.