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

sdGIVJPsWWszKPCGk, ghRJPsWWszKcJUg
JPsWWszK

IGHhMfqLeBpnullsPInfBH, LTDBpnullsPIBynwCrCQ
BpnullsPI

hqczQs, YgczRD

cz