An elevator has mass 680kg , not including passengers. The elevator is designed to ascend, at constant speed, a vertical distance of 21.0m (five floors) in 15.8s , and it is driven by a motor that can provide up to 35hp to the elevator. What is the maximum number of passengers that can ride in the elevator? Assume that an average passenger has mass 65.0 kg . Express you answer as an integer.