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: OyrqfQQnzOFUzrkDM, iBkQQnzOFewhjvO

Answer: QQnzOF


Question: WTnsmP, INnsIM

Answer: ns


Question: mbBPmOqQHWyJtVffFQjc, eYgPEBQHWyJtVuDxsxh

Answer:
QHWyJtV