#include <iostream>
#include <fstream>

using namespace std;

int main()
{
    /*int i,n,a[8001],b[8001],j,aux,frig;
    ifstream f("reactivi.in");
    ofstream g("reactivi.out");
    f>>n;
    for(i=0;i<n;i++){
        f>>a[i]>>b[i];
    }

    for(i=0;i<n-1;i++)
        for(j=i+1;j<n;j++){
            if(a[i]<a[j]){
                aux=a[i];
                a[i]=a[j];
                a[j]=aux;

                aux=b[i];
                b[i]=b[j];
                b[j]=aux;
            }
        }
    frig=1;
    int mini=a[0];
    int maxi=b[0];
    int ok,cont=1;
    for(i=1;i<n-1;i++)
        if(a[i]<=b[i-1] && a[i]<=maxi){
            mini=a[i];
            if(b[i]<maxi)
                maxi=b[i];
        }
        else{
            mini=-101;
            maxi=101;
            frig++;
        }
        //g<<a[i]<<" "<<b[i]<<'\n';
        //g<<a[i]<<" "<<b[i]<<'\n';
        /*{
            if((mini>a[i+1] && mini<b[i+1]) || maxi>a[i+1] && maxi<b[i+1]){
                    ok=1;
                    if(a[i]>mini)
                        mini=a[i];
                    if(b[i]<maxi)
                        maxi=b[i];
            }
            else
            {
                cont++;
                mini=a[i];
                maxi=b[i];
            }
        }*/
    //g<<frig;
    int i,n,a[8001],b[8001],j,aux,frig;
    ifstream f("reactivi.in");
    ofstream g("reactivi.out");
    f>>n;
    for(i=0;i<n;i++){
        f>>a[i]>>b[i];
    }

    for(i=0;i<n-1;i++)
        for(j=i+1;j<n;j++){
            if(a[i]>a[j]){
                aux=a[i];
                a[i]=a[j];
                a[j]=aux;

                aux=b[i];
                b[i]=b[j];
                b[j]=aux;
            }
        }
    frig=1;
    int mini=-101;
    int maxi=101;
    for(i=1;i<n;i++)
        if(a[i]<=b[i-1] && a[i]<=maxi){
            mini=a[i];
            if(b[i]<maxi)
                maxi=b[i];
        }
        else{
            mini=-101;
            maxi=101;
            frig++;
        }
        //g<<a[i]<<" "<<b[i]<<'\n';
    g<<frig;
}