这是一道ACM的关于交通运输的题目！主要用到了递归算法！有参考价值！-ACM on the subject of transport! Main uses recursive algorithm! Reference value!

双红外管计数1602显示，可用于公交车，教室等进行人数统计并显示-Infrared tube dual 1602 count showed that can be used for public transportation vehicles, such as statistics on the number of classroom and display