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

XHqQIPw, brqQIkAt
qQI

DnAzbgMtdPKsNCMpBfc, QdfXRkWREzbgMtdPKsGx
zbgMtdPKs

CTIGOMbKoJ, SibyGOMbqJ

GOMb