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

cUCQXEFSgRZjK, RYdvUQXEFSgRZVlwx
QXEFSgRZ

LiiFMMLGfNHVnnga, beXMMLGfNHVsjdfdN
MMLGfNHV

BnNqKxvazDJcovWLrwosLWTwM, gbDzDJcovWLrAhc

zDJcovWLr