Orange gwq come and solve it!!

You are given something, what is it?
You don't know, but you are curious about it.
You want to know what it is, but you can't.
It made you unpleasant, you are somewhat angry.
当你的野心还撑不起你的才华时，就应该静下心来评论一下。
Formally,you are given a 3-dimensional object. It is discribed a n\times m grid, which has its height on each grid, such like this.

This can be discribed as
2,1,2
1,1,0
1,1,1
And you want to start from the left-bottom-lower corner to the right-top-upper corner.

Find the shortest path, you only need to output the distance.
btw, i don't know the answer for the picture above 🙂