#include<bits/stdc++.h>
using namespace std;
struct meet{
	int start,end;
}a[10000];
bool cmp(meet x,meet y){
	return x.end<y.end;
}
int main(){
	int n;
	cin>>n;
	for(int i=0;i<n;i++){
		cin>>a[i].start>>a[i].end;
	}
	sort(a,a+n,cmp);
	int ans=0,e=0;
	for(int i=0;i<n;i++){
		if(a[i].start>=e){
			e=a[i].end;
			ans++;
		}
	}
	cout<<ans;
	return 0;
}