An unlimited supply of gasoline is available at one edge of a desert 800 miles wide, but there is no source on the desert itself. A truck can carry enough gasoline to go 500 miles (this will be called one ``load''), and it can build up its own refueling stations at any spot along the way. These caches may be any size, and it is assumed that there is no evaporation loss. What is the minimum amount (in loads) of gasoline the truck will require in order to cross the desert? What is the widest desert that can be crossed?