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

[Q]: CUxfOt, dyxfNp
[A]: xf


[Q]: zeuyZKwvIOfx, BlmZKwvspUt
[A]: ZKwv


[Q]: STvKOHq, XMGvKOdyM
[A]:
vKO