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

Example Input: kUoqCMPFTqGE, guoqCMPkwJs
Example Output: oqCMP

Example Input: fREVIdeTcakgFnwDWTVev, IbtXImseeTcakgFnwDYsKBAlux
Example Output: eTcakgFnwD

Example Input: huDKmOZzYVQieh, dsRQKmOZzYVIBkEVI
Example Output:
KmOZzYV