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

[Q]: DUhUbmfLuOFAQann, kwnzfLuOFAErR
[A]: fLuOFA


[Q]: IKrQfT, crrQRg
[A]: rQ


[Q]: DUuYgZtFwvffweSIkmLwByRHmqQn, oKgwvffweSIkmntXghUfBuN
[A]:
wvffweSIkm