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

Example Input: yywhNdZQkLSzbOvhluicHA, lfZQkLSzbOvhVC
Example Output: ZQkLSzbOvh

Example Input: haOsaSQcyodWhqQaC, BKLEUQcyodWhvVkmxBz
Example Output: QcyodWh

Example Input: hhBRWcTNEuugj, OEBRWcTNEuWYU
Example Output:
BRWcTNEu