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

NNpkdhvgT, BMkAkdhvrwV
kdhv

OgWFOfjNYmXVjBBvOdunIc, eGljKGnzFKFOfjNYmXVjdlqsT
FOfjNYmXVj

xCdxrv, qndxOS

dx