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: dpdpypyyppyyp
Example Output: pyyppyyp

Example Input: bbbgwbbbwg
Example Output: gwbbbwg

Example Input: kkkkkklklk
Example Output:
kkkkkk