In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
--------
Question: RtOkkgLvhgfGlX, vCOkgLvhzOa

Answer: kgLvh


Question: RJMYumLAlhmnbhzKRzIOWsGrxGu, VEViqlihmnbhzKRzIBArjAhYrz

Answer: hmnbhzKRzI


Question: USONKduSD, oOHNKdpc

Answer:
NKd