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

[Q]: oWwqraAz, uxTqraonu
[A]: qra


[Q]: sUdaWtsiRgqAYHykrHwjyDvZgD, MJdFXYiRgqAYHykrakSGHMr
[A]: iRgqAYHykr


[Q]: KdNdkO, FRNdGY
[A]:
Nd