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

Example Input: ezVsFayUPcrte, lfsFayUMPTqx
Example Output: sFayU

Example Input: CuizrSvJTRWZK, udyrSvJTRZzkS
Example Output: rSvJTR

Example Input: EGdcJxNVSPNbQQWhrUnpuNr, UKyioSPNbQQWhIWEKrmXl
Example Output:
SPNbQQWh