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: zzgghhgzggz
Example Output: ghhg

Example Input: nqnnffnnnfnq
Example Output: nnffnn

Example Input: clcccllclccc
Example Output:
lcccl