You have two strings, and . Find a string, , such that:
- can be expressed as where is a non-empty substring of and is a non-empty substring of .
- is a palindromic string.
- The length of is as long as possible.
For each of the pairs of strings ( and ) received as input, find and print string on a new line. If you’re able to form more than one valid string , print whichever one comes first alphabetically. If there is no valid answer, print instead.
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