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

Ex Input:
slTUxy, oqTUYa

Ex Output:
TU


Ex Input:
spGRUmIYuGl, qkqRUmItqU

Ex Output:
RUmI


Ex Input:
IbIUjEGvDgcExoP, sRbIjEGvDgqh

Ex Output:

jEGvDg