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

Ex Input:
SIIPePlrkftKkzfgdjg, JqNnXHrkftKkzOMUwmc

Ex Output:
rkftKkz


Ex Input:
haOsaSQcyodWhqQaC, BKLEUQcyodWhvVkmxBz

Ex Output:
QcyodWh


Ex Input:
RiDfUa, EtDfuE

Ex Output:

Df