#include<iostream>
#include<algorithm>
#include<vector>
using namespace std;
typedef pair<int,int> PII;
vector<PII> segs;
void merge(vector<PII> &segs){
    vector<PII> res;
    sort(segs.begin(),segs.end());
    int st=-1e9-10,ed=-1e9-10;
    for(auto b:segs){
        if(ed<b.first){
            if(st!=-1e9-10){
                res.push_back({st,ed});
            }
            st=b.first;
            ed=b.second;
        }
        else{
            ed=max(ed,b.second);
        }
    }
    if(st!=-1e9-10) res.push_back({st,ed});
    segs=res;
}
int main(){
    int n;
    cin>>n;
    while(n--){
        int l,r;
        cin>>l>>r;
        segs.push_back({l,r});
    }
    merge(segs);
    cout<<segs.size()<<endl;
    return 0;
}