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

[EX Q]: XWKEpwGRkfCFZGOyZQOoypx, lhQkmVqeRkfCFZGOyugPLqs
[EX A]: RkfCFZGOy

[EX Q]: SyweIt, ILweip
[EX A]: we

[EX Q]: VaLTFWEFakCLaZQeMXUhx, rpoFakCLaZtniWOVm
[EX A]:
FakCLaZ