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

hVQJkZyKfPoOQEukfAbXDpB, qpojyxWkZyKfPoOQEZkUI
kZyKfPoOQE

GrvtMjEvRlmN, ifGOWMjEvRPSOZK
MjEvR

NafBoJBGp, SUbXBoJBNftu

BoJB