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

Q: mmDhYqPJC, qThYqxW

A: hYq
****
Q: fdxgzAMP, xrcxgzYW

A: xgz
****
Q: ALIvkPOfnT, jMvkPOfpiopx

A:
vkPOf
****