instruction:
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.
question:
yybbkyybybkykk
answer:
yby


question:
oagaaaooaaogg
answer:
aaooaa


question:
ppvvvvpvavappv
answer:

pvvvvp