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:
iiddididijjiijd
answer:
didid


question:
fvvvvdvddvfdfd
answer:
vvvv


question:
zzzxzzzxzz
answer:

zzxzzzxzz