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

[Q]: XeQwOS, OuQwNR
[A]: Qw


[Q]: mCxQTIaXN, mWQTIaxzPT
[A]: QTIa


[Q]: UvYbfKFybXofcwLRrLRiK, BgMZKFybXofcVe
[A]:
KFybXofc