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

fCGEhfHvcRouHzNw, gtjBkhfHvcRouHee
hfHvcRouH

ktABEFESAVHZkkY, uMjxiESAVHZkZgWUte
ESAVHZk

kucvitJYLjZl, DPvitJYLvdIBCu

vitJYL