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

Ex Input:
ARGchkRez, kUwchkZPE

Ex Output:
chk


Ex Input:
FNVeaFmprNHqqtAaKv, iGBmrrMveaFmprNHqWWAvtht

Ex Output:
eaFmprNHq


Ex Input:
skZGHS, HsZGge

Ex Output:

ZG