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:
ssslwsswlws

Ex Output:
lwsswl


Ex Input:
mygyggggyym

Ex Output:
yggggy


Ex Input:
mpmmbmbmmpp

Ex Output:

pmmbmbmmp


