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

Ex Input:
hVQJkZyKfPoOQEukfAbXDpB, qpojyxWkZyKfPoOQEZkUI

Ex Output:
kZyKfPoOQE


Ex Input:
xMxyohPBlJIEBqghiMdBQPwq, xsBlJIEBqghlMosK

Ex Output:
BlJIEBqgh


Ex Input:
MmGKUgVch, rUWLGKUgirT

Ex Output:

GKUg