#include<iostream>
using namespace std;
#include<vector> 
#include<algorithm>
typedef pair<int , int > P;

bool cmp(P &a, P &b){
    return a.first < b.first;
}

/*主要的思想是先把区间排序，再合并，合并的过程讲的很明了*/
void  mg(vector<P> & t){

    vector<P> tmp;
    int i = 0;
    int l = t[0].first, r = t[0].second;

    for(i = 0; i < t.size()-1; i++){

        if(t[i + 1].first <= r && t[i + 1].second > r) r = t[i + 1].second;

        else if(t[i + 1].first > r) {
        tmp.push_back({l,r});
        l = t[i + 1].first;
         r = t[i + 1].second;
        }
    }
    tmp.push_back({l , r});//把最后的区间放进去

    t = tmp;
}

vector<P> t;

int main(){

    int n;
    cin>>n;
    for(int i = 0; i < n; i++) {
        int l, r;
        cin>> l >> r;
        t.push_back({l, r});
    }
    sort(t.begin(), t.end(),cmp);

    mg(t);
    cout<<t.size()<<endl;

    return 0;

}