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]: lOedgdw, aoedgpn
[EX A]: edg

[EX Q]: DuOSTtCMjS, oAOSTtjqwt
[EX A]:
OSTt