https://leetcode.com/problems/greatest-english-letter-in-upper-and-lower-case


Success


```python
import string

class Solution:
    def greatestLetter(self, s: str) -> str:
        for char in list(reversed(string.ascii_lowercase)):
            char2 = char.upper()
            if char in s and char2 in s:
                return char2
        return ""
```