Geraldine is making a simple AC electric generator for a science project using copper wire, cardboard, a nail and magnets. The first step in building the generator is wrapping the wire around and around the rectangular prism made from the cardboard and connecting it to small lightbulb, as shown in the figure. If Geraldine has 18 feet of wire and needs to leave 3 inches on each end to connect to the lightbulb, how many times can she wrap the wire around the cardboard prism?