Iva 非常喜欢糖果!她面前有一个 $n \times n$ 的网格,里面放满了糖果和障碍物。Iva 目前位于网格的左上角,她只能向下或向右移动,最终到达右下角。Iva 当前所在的格子没有障碍物。
### for main sections, #### for subsections, and the canonical structure for example I/O. The image URL is replaced with IMAGE_PLACEHOLDER as per the instructions. The document is now ready to be used as a competitive programming problem statement.