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

[Q]: VLxrvK, gvxrac
[A]: xr


[Q]: rqhQxQQDdYwemFiiwcfVx, cEQDdYwemFtwpfNJC
[A]: QDdYwemF


[Q]: XooCjtpTtAsdBd, aRoCjtpTkWry
[A]:
oCjtpT