In this task, you are given a string with duplicate characters ocurring in the string. You need to return the character which is ocurring with the maximum frequency. In case of a tie, return the character with the least ascii value.

Example Input: bcaupmhhjmizfywxbobwudtmmwelxtftdnrjpffmpsw
Example Output: m

Example Input: xkfrrlswmkxmkqycyjzdeqpxbkihtyljcbrpaqeluh
Example Output: k

Example Input: xltfbrkwsaatjegpavikehkjozsgqbtvjiunmfisc
Example Output:
a