An integer A (1 ≤ A ≤ 9).
An integer B (1 ≤ B ≤ 9).
An integer C (1 ≤ C ≤ 9).

### Example Input:

```
5 2 1
```

### Function Signature:
Write a function f(A, B, C) that takes in the input.
def f(A: int, B: int, C: int):
    '''
    A: an integer
    B: an integer
    C: an integer
    '''