CF1508A Binary Literature

A bitstring is a string that contains only the characters 0 and 1. Koyomi Kanou is working hard towards her dream of becoming a writer. To practice, she decided to participate in the Binary Novel Writing Contest. The writing prompt for the contest consists of three bitstrings of length $ 2n $ . A valid novel for the contest is a bitstring of length at most $ 3n $ that contains at least two of the three given strings as subsequences. Koyomi has just received the three prompt strings from the contest organizers. Help her write a valid novel for the contest. A string $ a $ is a subsequence of a string $ b $ if $ a $ can be obtained from $ b $ by deletion of several (possibly, zero) characters.

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In the first test case, the bitstrings 00 and 01 are subsequences of the output string: 010 and 010. Note that 11 is not a subsequence of the output string, but this is not required. In the second test case all three input strings are subsequences of the output string: 011001010, 011001010 and 011001010.