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

Example Input: jXqEDHTCxTiUAICWZJdpmYq, GBTCxTiUAICZKnLgZBXi
Example Output: TCxTiUAIC

Example Input: OrcQOvMBhmwP, mnWrzcQOvMBnLwI
Example Output: cQOvMB

Example Input: GClmhbPhGnijWTNr, eGxPhGnijKejHsF
Example Output:
PhGnij