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.
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Question: isivssiivivvi

Answer: ivvi


Question: gkkgkkkgkkggg

Answer: gkkgkkkgkkg


Question: avvvvaaaaavvzzv

Answer:
vvaaaaavv