The function `f(x)` takes an input string and reverses the position of alphabetic characters within the alphabet and reverses the order of numeric characters in the string.

[CODE]: 
```python
def f(x: str) -> str:
    result = []

    for char in x:
        if char.isalpha():
            result.append(chr(219 - ord(char)))  # 219 is the sum of ord('a') and ord('z')
        elif char.isdigit():
            result.append(char)
        else:
            result.append(char)
    
    result = ''.join(result)
    return result[::-1] if any(char.isdigit() for char in result) else result
```