Time limit
2s
Memory limit
256 MB
A monkey has escaped from a zoo and is traveling through the world. The monkey wants to move like a horse, so it tries to imitate the horse move used by a chess knight on a grid. In the table below, the cells marked x are the cells a horse can move to in one action. This move can jump over obstacles between the start and destination cells.
| x | x | |||
| x | x | |||
| Horse | ||||
| x | x | |||
| x | x |
However, the monkey can use this horse-like move at most K times. Every other move must go one cell up, down, left, or right. Diagonal movement is not allowed.
The monkey starts in the upper-left cell of the grid and must reach the lower-right cell. One adjacent move and one horse-like move each count as one action. Given the grid, find the minimum number of actions needed to reach the destination.
The first line contains the maximum number K of horse-like moves the monkey may use.
The second line contains the grid width W and height H.
Each of the next H lines contains W integers. 0 means an empty cell, and 1 means an obstacle. The monkey cannot move onto a cell with an obstacle. The start and destination cells are always empty.
1 <= W, H <= 200, and 0 <= K <= 30.
Print the minimum number of actions needed to reach the destination. If the destination cannot be reached, print -1.