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

Q: lMRuEThD, wqQRuEKp

A: RuE
****
Q: zBxuZfJgYrlRSzkmAktO, YNMgYrlRSzklmBOH

A: gYrlRSzk
****
Q: jCGFNrfxHvQ, citNrfxHpeLjj

A:
NrfxH
****