Hi struggling with the question here any help gratefully accepted.

Two courier companies offer services in the country of Old Aland. For any two towns, at least one of the companies offers a direct link in both directions between them. Aditionally, each company is willing to chain together deliveries( so if they offer a direct link from A to B, and B to C, and C to D for instance, they will deliver from A to D) Show that at least one of the two companies must be able to deliver packages between any two towns in Old Aland.