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

hVQJkZyKfPoOQEukfAbXDpB, qpojyxWkZyKfPoOQEZkUI
kZyKfPoOQE

HorIyjpfBFmKZQUIEoP, AcWOaOgVPmyjpfBFmKZQPFYiI
yjpfBFmKZQ

vDMgVZoZqbqUsRwA, JTrSoZqbqUsROyIOEs

oZqbqUsR