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

Q: nxoXDohHr, WcbkXDohFbJ

A: XDoh
****
Q: jinzsW, SMnzaW

A: nz
****
Q: ZeqqytqOoJW, OvifqqytqOzXXuQ

A:
qqytqO
****