An integer N (1 ≤ N ≤ 1,000,000), representing some quantity or size.
A string S_0 of length N consisting of lowercase English letters.
A string T of length N consisting of lowercase English letters.

### Example Input:

```
5
abcde
aaacc
```

### Function Signature:
Write a function f(N, S_0, T) that takes in the input. 
def f(N: int, S_0: str, T: str): 
    ''' 
    N: an integer 
    S_0: a string of length N
    T: a string of length N
    '''