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

Example Input: NUuLSmDjCKcJPc, lGGSLIDjCKcJBo
Example Output: DjCKcJ

Example Input: mmDhYqPJC, qThYqxW
Example Output: hYq

Example Input: WvstIDhbFCkfRAdgNUUwWTxh, TthbFCkfRAdDsQzB
Example Output:
hbFCkfRAd