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

CdRbREFMEDTXnEzgn, zHLEMMEDTXnEPH
MEDTXnE

yywhNdZQkLSzbOvhluicHA, lfZQkLSzbOvhVC
ZQkLSzbOvh

qPFSIDcqTnsOuzVAgJZabsZ, QCnIDcqTnsOuzhxPBkgbXD

IDcqTnsOuz