Balanced Paths

Given a 2D grid of integers where each cell can have a value of either 1 or -1, find the number of unique paths from the top-left corner (0, 0) to the bottom-right corner (n-1, m-1) such that the sum of values along the path is zero. You can only move right or down. If there are no valid paths, return 0. Input format: The first line contains two integers n and m (1 <= n, m <= 100), representing the dimensions of the grid. The next n lines each contain m integers (1 or -1). Output format: Print a single integer, the number of unique paths that satisfy the condition. Example: Input: 3 3 1 1 -1 1 -1 1 -1 1 1 Output: 2