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: DGvUCrUVlUnQBShkWnfnceGasvI, NfzGUnQBShkWnpLMnY

Answer: UnQBShkWn

Question: aiqZheFuLtXAGRCGNBTAX, ssnVdztXAGRCGNBTIqmSJLZcy

Answer: tXAGRCGNBT

Question: PayMkZxshcfOsZ, ZjPMeZxshcfEXmbt

Answer:
Zxshcf