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

Q: IKrQfT, crrQRg

A: rQ
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Q: bmZKWkYPqugcvzbHykblPzQLhK, tPUzKqugcvzbHypzk

A: qugcvzbHy
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Q: aRvrJlGRWLXDJwkGHukeMXN, pwUGRWLXDJwkhYgCBvA

A:
GRWLXDJwk
****