TASK DEFINITION: In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
PROBLEM: vJtmxQmHEq, yobgAtmxQmMeoLz

SOLUTION: tmxQm

PROBLEM: TdvkBvVyJcSdYGGPfnyml, rIvIvVyJcSdYhtxG

SOLUTION: vVyJcSdY

PROBLEM: KvpOGHlGRBGNzFuoQ, oAQQFLGRBGNzFbudVY

SOLUTION:
GRBGNzF