An integer \( l \) and an integer \( r \) (1 ≤ \( l \) ≤ \( r \) ≤ 10^9) with the constraint \( 0 \leq r - l < 1,000,000 \).

### Example Input:

```
1 9
```

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