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

[Q]: CiTNsbepy, DFNsbeZl
[A]: Nsbe


[Q]: bUHPpvVtFQNSpUdg, zggEFoKBHPpvVtFQNHXsc
[A]: HPpvVtFQN


[Q]: uDYXwgEDH, uBYXwgkg
[A]:
YXwg