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

nXVXIEGP, fkXIEkU
XIE

OgWFOfjNYmXVjBBvOdunIc, eGljKGnzFKFOfjNYmXVjdlqsT
FOfjNYmXVj

DMqxmouN, CcYqxmSQr

qxm