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.

Input: Consider Input: yyvjjyvvyvyvy

Output: vyvyv


Input: Consider Input: iiikciciki

Output: iii


Input: Consider Input: fcfbcffcccf


Output: fcccf