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

Ex Input:
GlAYDsKQoXy, IxDsKQuK

Ex Output:
DsKQ


Ex Input:
ZhHtTXaUmsQfUMNrnt, KvvebSXaUmsQfBspwM

Ex Output:
XaUmsQf


Ex Input:
hEzwOCbBoOZ, RRwOCbmvq

Ex Output:

wOCb