Customers $1,2,$ and $3$ are located on a large hill, with Customer $1$ and $2$ half way up

and Customer $3$ at the top. The height of the hill is such that a drone can only reach

Customer $3$ if it is launched from a truck delivering to either Customer $1$ or Customer $2$

$($or both$).$ Trucks and gig workers can deliver to Customer $3$ simply by driving up the

hill. Any of trucks, drones, or gig workers can deliver to Customers $1$ and $2.$ There are

no similar restrictions for customers $4,5,...,$ C$.$