An integer l (1 ≤ l ≤ 10^9).
An integer r (l ≤ r ≤ 10^9, and 0 ≤ 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
    '''