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

Q: GoodBOwvrki, kRCsdBOwvrakgiH

A: dBOwvr
****
Q: jkGcUm, dxGcSI

A: Gc
****
Q: LXPHFrVfk, qKjHFrPQ

A:
HFr
****