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: zzyoyyozyyyyzz

Output: zyyyyz


Input: Consider Input: hhmlmhhmmlhlmm

Output: hhmlmhh


Input: Consider Input: bwbwwbbtwbwbwwb


Output: wbwbw