A logistic company plans to purchase a cargo ship for $8 million. The annual revenue generated from the ship is $5 mil. and the annual operating cost is $2 mil. At the end of year 5 and 10, the ship will need some maintenance. The maintenance cost is $2 mil./time. After 15 years, the firm will liquidate the ship for $1.5 mil. If the discount rate is 8%, what is the present value of the ship?