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

[Q]: iYSNsY, HSSNhP
[A]: SN


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


[Q]: hsHUIFlvHDAnQASyX, ITLOXfIFlvHDAnQDs
[A]:
IFlvHDAnQ