5238: Ice Cave冰穴

You play a computer game. Your character stands on some level of a multilevel ice cave. In order to move on forward, you need to descend one level lower and the only way to do this is to fall through the ice.
The level of the cave where you are is a rectangular square grid of n rows and m columns. Each cell consists either from intact or from cracked ice. From each cell you can move to cells that are side-adjacent with yours (due to some limitations of the game engine you cannot make jumps on the same place, i.e. jump from a cell to itself). If you move to the cell with cracked ice, then your character falls down through it and if you move to the cell with intact ice, then the ice on this cell becomes cracked.
Let's number the rows with integers from 1 to n from top to bottom and the columns with integers from 1 to m from left to right. Let's denote a cell on the intersection of the r-th row and the c-th column as (r,c).
You are staying in the cell (r₁,c₁) and this cell is cracked because you've just fallen here from a higher level. You need to fall down through the cell (r₂,c₂) since the exit to the next level is there. Can you do this?

你玩电脑游戏。你的角色站在多层冰洞的某个层面上。为了继续前进，您需要降低一层，唯一的方法就是从冰上掉下来。

您所在的洞穴水平是一个由 n 行和 m 列组成的矩形方形网格。每个细胞要么由完整的冰组成，要么来自裂开的冰。从每个单元格中，您可以移动到与您的单元格侧面相邻的单元格（由于游戏引擎的某些限制，您无法在同一个地方进行跳跃，即从单元格跳到自身）。如果你移动到有裂冰的牢房，那么你的角色就会从里面掉下来，如果你移动到有完整冰块的牢房，那么这个牢房上的冰就会破裂。

让我们从上到下对整数从 1 到 n 的行和从左到右从 1 到 m 的整数的列进行编号。让我们将第 r 行和第 c 列交点上的单元格表示为 （r， c）。

你呆在牢房里(r1， c1)这个细胞被破解了，因为你刚刚从更高的层次掉到这里。你需要从牢房里掉下来(r2， c2)因为下一个级别的出口就在那里。你能做到吗？