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

Q: VRXUhOYfTul, JqZUhOYKq

A: UhOY
****
Q: FSwxBJ, iTwxAa

A: wx
****
Q: iCbjjqnKjnHUZBKPXo, GcqnKjnHUDPcP

A:
qnKjnHU
****