Given the task definition, example input & output, solve the new input case.
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: gocogccocco
Output: gocog
The substring 'gocog' is the longest possible substring that is also a palindrome. So this is a good example.

New input case for you: mpmmbmbmmpp
Output:
pmmbmbmmp