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:
aamaaahaham

Ex Output:
aamaa


Ex Input:
pppuupppppuu

Ex Output:
uupppppuu


Ex Input:
aaryaayaraar

Ex Output:

yaay