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

Ex Input:
skZGHS, HsZGge

Ex Output:
ZG


Ex Input:
HiEuutntEBpU, fdkqEuutntEBABdGZRND

Ex Output:
EuutntEB


Ex Input:
BSkZAthRvBBJiBEKL, UiCdJhthRvBBgG

Ex Output:

thRvBB