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

Q: SFQHJlK, dHfQHJoUC

A: QHJ
****
Q: fCGEhfHvcRouHzNw, gtjBkhfHvcRouHee

A: hfHvcRouH
****
Q: CwMFeOfvUFxATzaFxIkE, ZdKyAFeOfvUFxAZjfPuS

A:
FeOfvUFxA
****