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

Answer: KtWU


Question: OyXwTWbLByC, yODnTWbLWYzc

Answer: TWbL


Question: RqwVvzqtMfUMdsPzg, AArXrAqtMfUMdsPtJtxVvTjd

Answer:
qtMfUMdsP