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

[EX Q]: TnbLNKnNSs, NhDLNKnNRd
[EX A]: LNKnN

[EX Q]: ZhHtTXaUmsQfUMNrnt, KvvebSXaUmsQfBspwM
[EX A]: XaUmsQf

[EX Q]: tljMswoqXkeOiGlxwmAt, iHhNPoqXkeOilgF
[EX A]:
oqXkeOi