Find Intersection Point of Two Linked Lists

You are given two linked lists that may or may not intersect at some node. Each linked list is represented by space-separated integers ending with -1. Find the intersection point (the node where both lists merge), if any. If they do not intersect, output -1. Note: The lists are guaranteed to be linear before the intersection point. Example: Input: 1 2 3 -1 4 5 3 -1 Output: 3