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:
jbjjijijiibj

Ex Output:
jijij


Ex Input:
dvmdmdvmdmm

Ex Output:
mdm


Ex Input:
kkkkkklkklkkkk

Ex Output:

kkkklkklkkkk