#include<bits/stdc++.h>
using namespace std;
struct st{
	int s,l;
}sl[500005];
bool cmp(st x,st y){
	if(x.s==y.s) return x.l>y.l;
	else x.s>y.s;
}
bool flag[500005];
int ans=0;
int main(){
	int n;cin>>n;
	for(int i=0;i<n;i++){
		cin>>sl[i].s>>sl[i].l;
	}
	sort(sl,sl+n,cmp);
	memset(flag,0,sizeof(flag));
	for(int i=0;i<n;i++){
		if(flag[i])continue;
		else{
			ans++;
			int sls=sl[i].s;
			int sll=sl[i].l;
			flag[i]=1;
			for(int j=0;j<n;j++){
				if(!flag[j]&&sl[j].s<=sls&&sl[j].l<=sll){
					sls=sl[j].s;
					sll=sl[j].l;
					flag[j]=1;
				}
			}
		}
	}
	cout<<ans;
	return 0;
} 

求求了