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

[EX Q]: SeXNqRAbKdLuWXgb, npsIWRAbKdLuUWSbvuS
[EX A]: RAbKdLu

[EX Q]: YcgVJVACcQE, JsJVACcSz
[EX A]: JVACc

[EX Q]: UjCVBZCcVjOCJQGZskFcZnx, tVVcNbHwtVjOCJQGZskjTKWkpML
[EX A]:
VjOCJQGZsk