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

Example Input: CuizrSvJTRWZK, udyrSvJTRZzkS
Example Output: rSvJTR

Example Input: JXnHYuZvAYK, zhUYuZvASGhd
Example Output: YuZvA

Example Input: WCgKshUNXDizoHqyeANs, rQqFzZEDizoHqyeAaM
Example Output:
DizoHqyeA