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

Example Input: uHGHiARtdJbuG, OdZmiARtdrhC
Example Output: iARtd

Example Input: nFgMXUzpStDAybiwm, aNJrXUzpStDjp
Example Output: XUzpStD

Example Input: ojERIfKkLzInsSnLlrYWoji, ntMtLzInsSnLlrDlLsQpmjrQ
Example Output:
LzInsSnLlr