拦截导弹输入

第一行为导弹的个数



第二行为使用逗号分隔的导弹依次飞来的高度（雷达给出的高度数据是不大于30000 的正整数）



输出

这套系统最多能拦截多少导弹

-importation of the first missile interceptor missiles acts Number second acts use comma-separated missiles were flying in the height ( given the high degree of radar data is not more than 30,000 positive integers) output of this system the maximum number of missile interceptors