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.

Example Input: zhhzqzhhhqhqzqz
Example Output: hhzqzhh

Example Input: nweenneewnnn
Example Output: nweenneewn

Example Input: imvviivmimivivm
Example Output:
viiv