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

Ex Input:
atDgsOWuP, UJMgsOrwj

Ex Output:
gsO


Ex Input:
DUhUbmfLuOFAQann, kwnzfLuOFAErR

Ex Output:
fLuOFA


Ex Input:
jsHbwtyuCgFLYmeOPZbUrziy, ZwHgzcNCgFLYmeOOnSK

Ex Output:

CgFLYmeO