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

Example Input: bjjsMtBzzXIgYWPBZmaDL, iTxktmvBzzXIgYWPhbAyBE
Example Output: BzzXIgYWP

Example Input: skZGHS, HsZGge
Example Output: ZG

Example Input: AxOuIVBrnEOWck, ozEmymNuIVBrnEOwTi
Example Output:
uIVBrnEO

