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: mdmjjmdjdmjddj
Example Output: jmdjdmj

Example Input: uluqquluuqql
Example Output: uluqqulu

Example Input: suisuusuisssiis
Example Output:
isssi