一个正方形平面被分为N*N个单元格，其周围被墙包围，其中有一个滑块和一个坑，单

元格之间可能存在墙。每次操作可以将滑块往上下左右中的某一个方向滑动，滑块被滑动后

会朝滑动方向不断移动直到遇到墙或者掉入坑中为止。问最少滑动多少次能将滑块滑到坑

中。-Plane is a square divided into N* N a cell, which is surrounded by a wall, which has a slider and a pit, single

There may be a wall between the Cell. You can slide up and down in one direction around the slide, the slider is slid after each operation

We will continue to move toward the direction of the slide until it hits a wall or fall into the pit so far. How many times can slide the slider minimum pit ask slide

in.