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

fREVIdeTcakgFnwDWTVev, IbtXImseeTcakgFnwDYsKBAlux
eTcakgFnwD

eeoJEtGHPDvHck, ezPGHPDvHSf
GHPDvH

VbpfmBtOhW, DiyFpfmBtOloB

pfmBtO