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

[Q]: uqazNuZhdJhw, KbnrzNuZhBdp
[A]: zNuZh


[Q]: hGyDyQYdxCCuD, BQiFOyQYdxel
[A]: yQYdx


[Q]: cMRNYWPCbivSK, MpRYWPCbivPmTmW
[A]:
YWPCbiv