#include <iostream>
#include <cstring>
#include <cstdlib>
#include <cstdio>
#include <cmath>
#include <string>
#include <set>
#include <vector>
#include <algorithm>
using namespace std;
int a,b,c,d,l,s;
struct fun
{
	int x,y;
}f[5001];
int Compare(const void*elem1,const void*elem2)
{
	struct fun *elem3=(struct fun *)elem1;
	struct fun *elem4=(struct fun *)elem2;
	if (elem3->x != elem4 ->x) return elem3->x - elem4->x;
		else return elem3->y- elem4->y;
}
int main(void)
{
	freopen ("wooden.in","r",stdin);
	freopen ("wooden.out","w",stdout);
	scanf("%d",&a);
	for (b=0;b<a;b++) scanf("%d%d",&f[b].x,&f[b].y);
	qsort(f,a,sizeof(fun),Compare);
	c=f[0].y;
	d=0;
	while (d!=-1&&c!=-1)
	{
		for (b=1;b<a;b++)
			if (f[b].y>=c) 
			{
				c=f[b].y;
				f[d].y=-1;
				d=b;
			}
		f[d].y=-1;
		s++;
		c=-1;
		d=-1;
		for (b=1;b<a;b++)
			if (f[b].y!=-1)
			{
				c=f[b].y;
				d=b;
				break;
			}
	}
	printf("%d",s);
	fclose(stdin);
	fclose(stdout);
	return 0;
}