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

Q: RtAchtNymcswVk, FWRuRchtNymcswUkoERHyML

A: chtNymcsw
****
Q: VXSNlHzkB, EoNlHCiL

A: NlH
****
Q: PjgNReuGZ, qNOENReuQL

A:
NReu
****