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

[EX Q]: Owbiay, exbime
[EX A]: bi

[EX Q]: oZNKLmfxecDfkXEGFkRBYk, tReqkiExecDfkXEGtNZpJVRxC
[EX A]: xecDfkXEG

[EX Q]: UzFVxsBqYC, kwEVxsBqEEuc
[EX A]:
VxsBq