#include<bits/stdc++.h>
using namespace std;
struct time{int begin,end;}a[1010];
int n;
bool cmp(time b,time c){
	if(b.end<c.end)return true;
    if(b.end==c.end&&b.begin<c.begin)return true;
    return false;
}
int main(){
	cin>>n;
	for(int i=0;i<n;i++)cin>>a[i].begin>>a[i].end;
	sort(a,a+n,cmp);
	int ans=0;
	for(int i=1,t=-1;i<=n;++i)if(a[i].begin>=t){
		ans++;
		t=a[i].end;
	}
	cout<<ans;
}