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: SJIkEibGrqcrOBgGjYjJc, EervOGrqcrOBgGJZyx
Example Output: GrqcrOBgG

Example Input: wWpwbZKAUYUIbxMLHxN, AYdqvPFZKAUYUIBIbWA
Example Output:
ZKAUYUI