Canonicalized Input Description:

Two strings S and T consisting of lowercase English letters.
1 ≤ |S|, |T| ≤ 2 × 10^5
|S| = |T|

### Example Input:

```
azzel
apple
```

### Function Signature:
Write a function f(S, T) that takes in the input.
def f(S: str, T: str):
    '''
    S: a string
    T: a string
    '''