#include<iostream>
#include<stdio.h>
#include<algorithm>
using namespace std;
FILE *f,*g;
struct reactivi
{
    int x,y;
};
int cmp(reactivi a,reactivi b)
{
    return a.y<b.y;
}
reactivi a[8000],aux;
int i,n,m,j,nr=1;
int main()
{
    f=fopen("reactivi.in","r");
    g=fopen("reactivi.out","w");
    fscanf(f,"%d",&n);
    for(i=0;i<n;i++)
        fscanf(f,"%d %d\n",&a[i].x,&a[i].y);
    sort(a,a+n,cmp);
    for(j=0,i=1;i<n;i++)
        if(a[j].y<a[i].x)
        {nr++;
        j=i;}
        fprintf(g,"%d",nr);
}