Canonicalized Input Description:

A string \( s \) of length between 1 and 10^5, consisting of lowercase English letters.
A string \( t \) of length between 1 and 10^5, consisting of lowercase English letters.

### Example Input:

```
contest
son
```

### 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
    '''