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

Example Input: hUpEbyvEcQ, dHpEbyvEvwsXcN
Example Output: pEbyvE

Example Input: aeQjEeiWGONmzGimhGiw, RIEeiWGONmOZuVYr
Example Output: EeiWGONm

Example Input: OargYBQmmnTK, vNvwgYBQmmkxvRqP
Example Output:
gYBQmm