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

Ex Input:
rqhQxQQDdYwemFiiwcfVx, cEQDdYwemFtwpfNJC

Ex Output:
QDdYwemF


Ex Input:
ZRjPgqbLL, uIsmPgqbBB

Ex Output:
Pgqb


Ex Input:
wEglgkNdL, iVlgkNAf

Ex Output:

lgkN