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.

Example Input: asooassooasso
Example Output: oo

Example Input: lllaaulaul
Example Output: lll

Example Input: itiuiiiituut
Example Output:
iiii