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

FNVeaFmprNHqqtAaKv, iGBmrrMveaFmprNHqWWAvtht
eaFmprNHq

krnkpodgfpCKtfCqyzUbymWbxi, DydgSWpCKtfCqyzDaMsjqc
pCKtfCqyz

biFGcxdedNFi, JbFGcxdLjW

FGcxd