解决ACM会场安排问题：

学校的小礼堂每天都会有许多活动，有时间这些活动的计划时间会发生冲突，需要选择出一些活动进行举办。小刘的工作就是安排学校小礼堂的活动，每个时间最多安排一个活动。现在小刘有一些活动计划的时间表，他想尽可能的安排更多的活动，请问他该如何安排-Solve the ACM venue arrangements: the small hall of the school every day, there are many activities, time of these activities scheduled time conflict, need to choose some of the activities organized. Liu' s work is to arrange the activities of the school auditorium, each time up to arrange an activity. Liu has some of the activities planned schedule, he would like to arrange more activities as much as possible, I ask him how to organize