Antipalindrome#2197
A palindrome is a string that reads the same forwards and backwards. You are given a string . Find its longest substring that is not a palindrome.
The input contains the string . It consists only of lowercase Latin letters, is not empty, and its length does not exceed characters.
Output the answer; if there are several answers, choose the lexicographically minimal one. If all substrings of are palindromes, output NO SOLUTION.
Example 1