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:
bbbgwbbbwg

Ex Output:
gwbbbwg


Ex Input:
hssxsxshsxsssh

Ex Output:
sxshsxs


Ex Input:
xxbfbfxxxffxfxx

Ex Output:

fxxxf