Shortest Path in a Maze

Given a 2D grid representing a maze with '0's (open path) and '1's (walls), find the length of the shortest path from the top-left corner (0, 0) to the bottom-right corner (n-1, m-1). You can move up, down, left, and right. If there is no path, return -1. For example, given the input: 0 0 1 0 0 0 1 0 1 0 0 0 0 1 1 0 The output should be: 7