An integer A (1 ≤ A ≤ 10^9).
An integer B (A ≤ B ≤ 10^9).
An integer K (1 ≤ K ≤ 100).

### Example Input:

```
3 8 2
```

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