Canonicalized Input Description:

An integer N (2 ≤ N ≤ 100), representing some quantity or size.
An integer M (2 ≤ M ≤ 100), representing some quantity or size.
An integer A (0 ≤ A ≤ 10), representing some quantity or size.
A grid of size NxM, where each cell contains one of the following characters: {'#', '.', 'S', 'G'}.

### Example Input:

```
3 3 2
S#.
...
.#G
```

### Function Signature:
Write a function f(N, M, A, grid) that takes in the input.
def f(N: int, M: int, A: int, grid: List[str]):
    '''
    N: an integer
    M: an integer
    A: an integer
    grid: a list of strings
    '''