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: puppppppppup

Output: puppppppppup


Input: Consider Input: mmeeppepem

Output: eppe


Input: Consider Input: titttmmtmimmmt


Output: tmmt