Find maximum-occurring character in a string

Problem

Given a non-empty string s, return the character that occurs the most times in s.

Tie-breaking

If multiple characters have the same maximum frequency, return the one whose first occurrence index in s is smallest.

Input

• A string s (characters are case-sensitive).

Output

• A single character: the maximum-occurring character under the tie-break rule.

Constraints

• 1 <= len(s) <= 2 * 10^5
• s may contain any printable ASCII characters (treat each distinct character separately).

Example

• Input: "abcaac"
• Frequencies: a=3, c=2, b=1 → Output: a