An integer N (1 ≤ N ≤ 2 × 10^5), representing some quantity or size.
A list of integers P of size N, which is a permutation of the integers from 1 to N.

### Example Input:
```
4
1 3 2 4
```

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