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.

Ex Input:
hssxsxshsxsssh

Ex Output:
sxshsxs


Ex Input:
gnfnggnfgngfgn

Ex Output:
fnggnf


Ex Input:
nbuuunbbnuuu

Ex Output:

uuunbbnuuu