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

Example Input: xMxyohPBlJIEBqghiMdBQPwq, xsBlJIEBqghlMosK
Example Output: BlJIEBqgh

Example Input: OVZxWYzAAxG, rStOxWYzJeoC
Example Output: xWYz

Example Input: juZoLOHFj, AlXZoLOlXw
Example Output:
ZoLO