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:
kskhhshhhhkhhh

Ex Output:
hhhkhhh


Ex Input:
tdtedtettddee

Ex Output:
tdt


Ex Input:
uspupuuususp

Ex Output:

pup