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

Q: feYKRk, PrYKMW

A: YK
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Q: egYXVtCPvWxP, VMOolyVtCPvWjIx

A: VtCPvW
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Q: cshVEkpaR, cJzVEkrv

A:
VEk
****