In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.

[Q]: ZRjPgqbLL, uIsmPgqbBB
[A]: Pgqb


[Q]: UovaYpHjYSQzrfsxRfvIZE, pUOFxIKOGQzrfsxRfvIjrza
[A]: QzrfsxRfvI


[Q]: AYPJFmtlQCLthsbX, unOERktlQCLtuMH
[A]:
tlQCLt