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

Example Input: YHLJZrFQ, aSLJZQuo
Example Output: LJZ

Example Input: biAihydBoNlzR, IAloNhydBolwUz
Example Output: hydBo

Example Input: atIWEqGggjpSHmhY, wbFAnMEqGggjpUg
Example Output:
EqGggjp