An integer N (1 ≤ N ≤ 9999), representing a four-digit number. The number of datasets does not exceed 10,000. The end of input is indicated by a line containing only 0000. 

### Example Input:

```
6174
2012
3333
0000
```

### Function Signature:
Write a function f(inputs) that takes in the input.
```python
def f(inputs: List[int]): 
    ''' 
    inputs: a list of integers
    '''
```