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

sGrHRmELarByxp, cDCUnmELarBXbEfM
mELarB

OFbCjZDoRRlLsMU, DcCjZDoRRtld
CjZDoRR

uQnSLqDRbeFWyxHfNXKPINh, CQDRbeFWyxHfzPhM

DRbeFWyxHf