o be at least as high as Mark.  Each of the N cows has a height, weight, and strength. A cow's strength indicates the maximum amount of total weight of the cows that can be stacked above her.    Given these constraints, Bessie wants to know if it is possible for her team to build a tall enough stack to catch the frisbee, and if so, what is the maximum safety factor of such a stack.  The safety factor of a stack is the amount of weight that can be added to the top of the stack without exceeding any cow's str