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

[Q]: EPUxsZtt, KgxsZuXM
[A]: xsZ


[Q]: vFuggVITQuctFG, hdCIWWuuggVITQwr
[A]: uggVITQ


[Q]: khRibxzM, qsRibdj
[A]:
Rib