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

Ex Input:
AxAmDG, LTAmEV

Ex Output:
Am


Ex Input:
kIBDjQLEZepVNHqnKqhine, hTZepVNHqnYTajyzv

Ex Output:
ZepVNHqn


Ex Input:
ruviSP, ROviRr

Ex Output:

vi