Design a logic diagram

Basically I want you to design a logic circuit that solve a problem look at the assignment that I have uploaded just do the first part of it
The problem is building materials supply company has two trucks of length 15 metres and 10 metres. They have a contract to supply building materials (brick, steel beams, glass panes etc...) to the site of a new university building. There are four unloading bays at the delivery site. Each unloading bay is of length 5 meters. The construction site manager has installed sensors that remotely allow the supply company to know which of the unloading bays are free. The building supply company can then automatically determine which of its two trucks to dispatch on any particular day. Priority is to be given to the 15 metre truck if there are sufficient unloading bays available.