Types: 
h: int, 
w: int, 
n: int, 
field: List[str]

Ranges: 
2 ≤ h ≤ 30, 
2 ≤ w ≤ 30, 
2 ≤ n ≤ 30, 
field[i][j] in {'A'-'Z', '.'}

Addtl Info: 
field is a list of h strings, each of length w