In this task you will be given a string and you should find the longest substring that is a palindrome. A palindrome is a string that is the same backwards as it is forwards. If the shortest possible palindrome is length 1 you should return the first character.

Q: jxxjxjxxaaaj

A: xxjxjxx
****
Q: rrrjjmmrmrm

A: mrmrm
****
Q: dddtztttdt

A:
ddd
****
