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:
IzwlZDJSEFPxfIud, xwWSYwlZDJSEFPbvSXTlS

Ex Output:
wlZDJSEFP


Ex Input:
CaupprPvlorJCEx, QpJTrPvlorIFgZh

Ex Output:

rPvlor