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

Example Input: gHFwDorPbNPORVgdLW, AfqDQvCGFwDorPbNPVPVmbQ
Example Output: FwDorPbNP

Example Input: jdLbZSCzaAHGbNwILGmudOH, RdIPuEYJvUZSCzaAHGbNduLToRC
Example Output: ZSCzaAHGbN

Example Input: StwRWnOwFNycmfTWqUq, VOuzlnxWnOwFNycWYQP
Example Output:
WnOwFNyc