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

[EX Q]: hVQJkZyKfPoOQEukfAbXDpB, qpojyxWkZyKfPoOQEZkUI
[EX A]: kZyKfPoOQE

[EX Q]: dZJWBGoeoMepPoTg, pekBGoeoMeQP
[EX A]: BGoeoMe

[EX Q]: PcOFovJxfLhgcy, munovJxfqH
[EX A]:
ovJxf