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

Example Input: aBlALASwuwTZmy, MdwASwuwIW
Example Output: ASwuw

Example Input: haOsaSQcyodWhqQaC, BKLEUQcyodWhvVkmxBz
Example Output: QcyodWh

Example Input: IQUHoPutPfew, XpUHoPujGD
Example Output:
UHoPu