An integer Y1 (1 ≤ Y1 ≤ 10^18).
An integer M1 (1 ≤ M1 ≤ 12).
An integer D1 (1 ≤ D1 ≤ 31).
An integer Y2 (1 ≤ Y2 ≤ 10^18).
An integer M2 (1 ≤ M2 ≤ 12).
An integer D2 (1 ≤ D2 ≤ 31).
Additional constraints: 1 ≤ Y1 ≤ Y2 ≤ 10^18

### Example Input:

```
2015 3 13 2015 3 13
```

### Function Signature:
Write a function f(Y1, M1, D1, Y2, M2, D2) that takes in the input.
def f(Y1: int, M1: int, D1: int, Y2: int, M2: int, D2: int):
    '''
    Y1: an integer
    M1: an integer
    D1: an integer
    Y2: an integer
    M2: an integer
    D2: an integer
    '''