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

Ex Input:
mOGzbnDXWnNurkBXtcqZ, NLahGzbnDXWnNYgMTOR

Ex Output:
GzbnDXWnN


Ex Input:
YWNPkA, LuNPnN

Ex Output:
NP


Ex Input:
PCzbOUyGn, wbJbOUyoni

Ex Output:

bOUy