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:
jjsjtjtsssttsjt

Ex Output:
tssst


Ex Input:
qhqfqqhqqqfqq

Ex Output:
qqhqq


Ex Input:
xlxwxlwlwllxllw

Ex Output:

wllxllw