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

Q: wkVVZREWhcSCpvCTB, ZQWhcSCpvCDVUY

A: WhcSCpvC
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Q: HXYkGv, GCYksu

A: Yk
****
Q: mQMWKudmuCIf, DrrKudmSdOH

A:
Kudm
****