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

Example Input: uRLpAWCotLmxcSmKyvo, laotLmxcSmKyBwVfJB
Example Output: otLmxcSmKy

Example Input: BmwpAnWJ, klVwpAFw
Example Output: wpA

Example Input: AzLXylApScOJloMxCMpQbrGD, MZtHWkcOJloMxCMkwH
Example Output:
cOJloMxCM