An integer \( N \) (1 ≤ \( N \) ≤ 2 \times 10^5), representing the length of two strings.
A string \( S \) of length \( N \) consisting of lowercase English letters.
A string \( T \) of length \( N \) consisting of lowercase English letters.

### Example Input:

```
5
azzel
apple
```

### Function Signature:
Write a function f(N, S, T) that takes in the input.
```python
def f(N: int, S: str, T: str):
    '''
    N: an integer
    S: a string
    T: a string
    '''
```