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: radadaadrar
Example Output: adada

Example Input: kskhhshhhhkhhh
Example Output: hhhkhhh

Example Input: ckckttkkktcckc
Example Output:
tkkkt

