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. 
def f(A: int, B: int, K: int): 
    ''' 
    A: an integer 
    B: an integer 
    K: an integer 
    '''