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

Example Input: lPhVhAQZWJDrvzcEaGEwKgZAuJI, qIJDrvzcEaGDRCRrB
Example Output: JDrvzcEaG

Example Input: yywhNdZQkLSzbOvhluicHA, lfZQkLSzbOvhVC
Example Output: ZQkLSzbOvh

Example Input: ZmbchgdLyQIcRF, IqgdLyQIcINPGcgQ
Example Output:
gdLyQIc

