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

Q: GnElFKBIoYmAdvz, GrElFKBIoMo

A: ElFKBIo
****
Q: SFQHJlK, dHfQHJoUC

A: QHJ
****
Q: tDMYZXyKfb, dOlZXyKzt

A:
ZXyK
****