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题目描述

同上迷宫定义，求从 (0,0) 到 (n-1,m-1) 的最少步数（每步上下左右），若无法到达输出 -1。

输入输出示例

输入：

3 3
0 0 0
0 1 0
0 0 0

输出：

4