#include<iostream>
using namespace std;
int start_time[10000], end_time[10000];
int n, sum = 0;
void sort_time(void) {
	for (int i = 0;i < n;i++) {
		for (int m = 0;m < n;m++) {
			if (end_time[m] > end_time[i] && m != i) {
				int p = end_time[i];
				end_time[i] = end_time[m];
				end_time[m] = p;
				 p = start_time[i];
				start_time[i] = start_time[m];
					start_time[m] = p;
			}
		}
	}
}
int main() {
	cin >> n;
	for (int i = 0;i < n;i++) {
		cin >> start_time[i] >> end_time[i];
		for (int m = 0;m < i;m++) {
			if (start_time[i] == start_time[m]) {
				if (end_time[i] >= end_time[m]) {
					start_time[i] = -1;
					end_time[i] = -1;
					i--;
					n--;
				}
				else if (end_time[i] < end_time[m]) {
					end_time[m] = end_time[i];
					start_time[m] = start_time[i];
					start_time[i] = -1;
					end_time[i] = -1;
					i--;
					n--;
				}
			}
		}
	}

	sort_time();
	
	
	int h = 0;
	for (int i = 1;i < n;i++) {
		
		if (start_time[i] >= end_time[h]) {
			h = i;
			
			sum++;
		
		}
	}

	cout << sum+1;
	return 0;
}

感觉一开始去掉相同开始时间的步骤有点多此一举，然后排序那里我只会手动排了，用了sort的话我不能保证他的结束时间会一一对应。