Two cars, 360 kilometers apart, begin driving toward each other on a long, straight highway. One car travels 80 km per hour and the other 100 km per hour. At the same time, a canary, starting on one car, flies back and forth between two cars as they approach each other. If the canary flies 120 km per hour and spends no time to turn around at each car, how far has it flown when the cars collide?