#include<fstream>
using namespace std;
ifstream in("reactivi.in");
ofstream out("reactivi.out");
struct interval{int x,y;};
interval a[8001],t;
int n;
int main()
{
	int i,j,nr=1;
	in>>n;
	for(i=0;i<n;i++)
		in>>a[i].x>>a[i].y;
	for(i=0;i<n;i++)
		for(j=i+1;j<n;j++)
			if(a[i].y>a[j].y)
			{
				t=a[i];
				a[i]=a[j];
				a[j]=t;
			}
	for(i=1,j=0;i<n;i++)
	if(a[j].y<a[i].x)
	{
		nr++;
		j=i;
	}
	out<<nr;
	return 0;
}