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

[Q]: wNiHcaiUPHnjp, aSTmjcaiUPHFzOu
[A]: caiUPH


[Q]: PQSFjlnU, kTSFjMUh
[A]: SFj


[Q]: yiKkIxbKvNk, znaIxbKggg
[A]:
IxbK