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

Q: GBTHKtWUzK, ovVNKtWUmVJF

A: KtWU
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Q: osmJJcZlDAXBgJFsJKa, rzPNlDAXBgJYrgXlH

A: lDAXBgJ
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Q: Owbiay, exbime

A:
bi
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