Shortest Path in Maze

You are given a 2D grid representing a maze where '0' is a free cell and '1' is a wall. Your task is to find the length of the shortest path from the top-left corner (0, 0) to the bottom-right corner (m-1, n-1). You can move up, down, left, or right. If there is no valid path, return -1. Input format: The first line contains two integers m and n (1 <= m, n <= 100). The next m lines each contain n integers (0 or 1). Output format: An integer representing the length of the shortest path or -1 if no path exists. Example: Input: 3 3 0 1 0 0 0 0 1 1 0 Output: 4