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

Q: nYoRQU, gQoRZQ

A: oR
****
Q: goyZUz, QryZlD

A: yZ
****
Q: mXHhaCEIwqwEZcz, JZPXbYHhaCEIwZmna

A:
HhaCEIw
****