First Non Repeating Char

Return first non-repeating character in a string. Example: "aabccbd" => "d"

Your task

Implement this function:

def first_non_repeating_char(s: str) -> str:

Write the function only — the arguments are read for you and the return value is printed automatically.

Arguments arrive as one Python literal per line, in this order: s.

Example

Input

'aabccbd'

Output

'd'