A firm supplies its retail outlets from a central warehouse. Trucks can leave the warehouse as

early as $3$am to make pallet$-$load deliveries and may return at any time. The trucks may also pick

up empty pallets and supplies from vendors in the general area. Pickups are allowed only after all

deliveries on a route are made. The distance matrix shows the distance between every stop, with

stop $0$ representing the warehouse. The total time on a route may be $40$ hours and total route

distance may be up to $1,400$ miles. Team drivers are used so that no overnight breaks are

required, but one$-$hour rest breaks are required at $12$ noon and $8$pm each day. Average driving

speed is taken to be $30$ miles per hour. Additional data about the stops are as follows