Highest Frequency Character

You are given a string s. Your task is to find the character that appears the most in s. If there is a tie for the highest frequency, output the character that appears first in s.

If the string is empty, output None.

Note: The input string may contain letters, digits, or special characters. You should consider all characters.

Example: For s = "aabbbcc", the answer is b, because although both 'a' and 'b' appear frequently, 'b' reaches the maximum count earlier in the string when considering the tie-breaking rule.

inputFormat

The input consists of a single line containing the string s.

outputFormat

Output the character with the highest frequency based on the conditions described. If the string is empty, output None.

aabbbcc

b