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

Ex Input:
QvtDqzQiSknPbRCG, hVxHdqzQiSknPbumdpNIf

Ex Output:
qzQiSknPb


Ex Input:
nFgMXUzpStDAybiwm, aNJrXUzpStDjp

Ex Output:
XUzpStD


Ex Input:
IQIHqbEhpVuNATp, GIJIHqbEhpzWb

Ex Output:

IHqbEhp