They each have a rifle and take it in turns to shoot at each other. They also, however, have varying degrees of accuracy of shot: one hits his target 50% of the time, one hits his target 70% of the time and the other hits his target 90% of the time. In the interest of fairness, the man with the worst shot is allowed to shoot first (the man with the 70% shot next, etc). What should he do?