An integer N (1 ≤ N ≤ 100000), representing some quantity or size.
A list of integers a of size N, where each integer is between 1 and 10^9.

### Example Input:

```
3
1 1 2
```

### Function Signature:
Write a function f(N, a) that takes in the input.
```python
def f(N: int, a: List[int]):
    '''
    N: an integer
    a: a list of integers
    '''
```