#include <bits/stdc++.h>

using namespace std;

typedef pair<int, int> pii;

bool ordena(pii a, pii b){
    return a.second <= b.second;
}

int main(){
    int n, n_consultas=0, a, b, ult_fim = -1;
    vector <pair <int, int> > horarios;
    cin >> n;

    for(int i=0; i<n; i++){
        cin >> a >> b;
        horarios.push_back({a, b});
    }

    sort(horarios.begin(), horarios.end(), ordena);

    for(int i=0; i<n; i++){
        if(horarios[i].first >= ult_fim){
            n_consultas++;
            ult_fim = horarios[i].second;
        }
    }

    cout << n_consultas << endl;

    exit(0);
}