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

[Q]: QqtCFzXHPNFXx, XECFzXHPSGwUuk
[A]: CFzXHP


[Q]: dxqZUOvRprXyFfjQfTWBhR, biSVjOvRprXyFfDtuFWQ
[A]: OvRprXyFf


[Q]: zqlOipYXx, CqOipwrY
[A]:
Oip