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

Example Input: OgWFOfjNYmXVjBBvOdunIc, eGljKGnzFKFOfjNYmXVjdlqsT
Example Output: FOfjNYmXVj

Example Input: andNlOdIcQMyZvc, vCMENolkslOdIcQMyZJtCFo
Example Output: lOdIcQMyZ

Example Input: nmutfX, BeutiA
Example Output:
ut