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

GrvtMjEvRlmN, ifGOWMjEvRPSOZK
MjEvR

ZKMRTxCxbsbX, iovHrMRTxCxbsjv
MRTxCxbs

TnHJcxtwcZ, XFdHJcxNKw

HJcx