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.

pmrdeazqwlsicttsnzzaqiuobgcgabqkqwthmammlviwcl
a

eszudurddbdbvvgnuebijuyswglflxnbxnqmskolmofg
b

ujksgfumsawrdverpmngnjecntcxxxznwcoxxhkx

x