#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
struct node{
	int x,y;
}a[6000];
int i,j,k,n,m,p;
int f[6000];
int tail;
bool cmp(node a,node b){
	if (a.x>b.x) return false;else{
		if (a.x<b.x) return true;else{
			return (a.y<b.y);
		}
	}
}
int main()
{
	freopen("wooden.in","r",stdin);
	freopen("wooden.out","w",stdout);
	scanf("%d",&n);
	for (i=1;i<=n;i++)
		scanf("%d%d",&a[i].x,&a[i].y);
	sort(a+1,a+n+1,cmp);
	f[1]=a[1].y;
	tail=1;
	for (i=2;i<=n;i++){
		int minx=200000000;
		for (j=1;j<=tail;j++){
			if (f[j]<a[1].y)
				if (f[j]>minx){
					minx=f[j];
					p=j;
				}
			if (minx==200000000){
				tail++;
				f[tail]=a[i].y;
			}else{
				f[j]=a[i].y;
			}
		}
	}
	printf("%d",tail);
	return 0;
}