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

Q: JAGuNgaUudP, eojvKNgaUuQg

A: NgaUu
****
Q: nYoRQU, gQoRZQ

A: oR
****
Q: WnQZoE, nvQZhC

A:
QZ
****