Mytsyk's Holiday#53
There is a rectangular hangar of size M \times N (horizontal by vertical). The hangar floor is covered with triangular tiles, numbered as shown in the image below.
Mytsyk can move from one tile to an adjacent tile (sharing a common side) in a single step. Starting from tile , what is the minimal number of steps Mytsyk must take to reach tile , where a piece of cheese is located?
The first line contains two integers and (1 \leq M, N \leq 30000) — the dimensions of the hangar.
The second line contains two integers: , the number of the tile where Mytsyk starts, and , the number of the tile with the cheese.
Print a single integer — the minimal number of steps Mytsyk must take.
Example 1