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

Q: OyrqfQQnzOFUzrkDM, iBkQQnzOFewhjvO

A: QQnzOF
****
Q: cjDuPZOHjystHnF, okWVdUDuPZOHjSCaEecP

A: DuPZOHj
****
Q: ZKfYRpyPSxPGZvH, hvwVKRQyPSxPGZPLpxB

A:
yPSxPGZ
****
