Canonicalized Input Description:

A string \(s\) consisting of lowercase English letters (1 ≤ |s| ≤ 10^5).
A string \(t\) consisting of lowercase English letters (1 ≤ |t| ≤ 10^5).

### Example Input:

```
contest
son
```

### Function Signature:
Write a function f(s, t) that takes in the input.
```python
def f(s: str, t: str):
    '''
    s: a string
    t: a string
    '''
```