An integer \( \text{len}(S) \) (9 ≤ \( \text{len}(S) \) ≤ 50), representing the length of the string.
A string \( S \) of length \( \text{len}(S) \), consisting of uppercase English letters and ending with a specific suffix.

### Example Input:

```
CODEFESTIVAL
```

### Function Signature:
Write a function f(S) that takes in the input.
```python
def f(S: str):
    '''
    S: a string
    '''
```