假设要在足够多的会场里安排一批活动，并希望使用尽可能少的会场，请写一个程序计算出最小的会场个数。



[输入要求]



有多组测试数据，第一行有1 个正整数，表示有k 个待安排的活动。接下来的k 行中，每行有2 个正整数，分别表示k 个待安排的活动开始时间和结束时间。时间以0 点开始的分钟计,所有正整数都在100000以内

-Assumed to be a sufficient number of arrangements for a number of activities inside the venue, and hoped to use as little as possible of the venue, please write a program to calculate the minimum number of venues. [Input required] how test data set, the first line has a positive integer k expressed activities were to be arranged. The next k lines, each line has two positive integers k, respectively, the activities were to be arranged start time and end time. Time 0:00 minutes beginning, all the positive integers are less than 100,000