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: ZRjPgqbLL, uIsmPgqbBB

Answer: Pgqb


Question: CxwZWv, mkwZgM

Answer: wZ


Question: CXXVKKv, FnzXVKYuw

Answer:
XVK