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

[EX Q]: BVipiZoGXaWdjmDsxWP, yxppsiYkiZoGXaWdjoDRuKW
[EX A]: iZoGXaWdj

[EX Q]: atDgsOWuP, UJMgsOrwj
[EX A]: gsO

[EX Q]: UNQzeBAF, MJYzeBsB
[EX A]:
zeB