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

Ex Input:
FSwxBJ, iTwxAa

Ex Output:
wx


Ex Input:
CiElmOvTqJGVJkfSaDRzE, EjDJwMyxTvTqJGVJkfluB

Ex Output:
vTqJGVJkf


Ex Input:
GTmdEQez, qSmdEQCUn

Ex Output:

mdEQ