#include <stdio.h>
#include <stdlib.h>
typedef struct{
    int x,y;
}vulcani;
vulcani v[8000];
int cmpfunc (const void * p, const void * q)
{
    vulcani *pa=(vulcani*)p,*qb=(vulcani*)q;
    vulcani a=(*pa),b=(*qb);
    if(a.x<b.x)return -1;
    if(a.x>b.x)return 1;
    return 0;
}
int main()
{
    freopen("reactivi.in","r",stdin);
    freopen("reactivi.out","w",stdout);
    int n,i,minc,maxc,k=1;
    scanf("%d",&n);
    for(i=0;i<n;i++)
        scanf("%d %d",&v[i].x,&v[i].y);
    qsort(v,n,sizeof(v[0]),cmpfunc);
    maxc=v[0].y;
    for(i=1;i<n;i++)
        if(v[i].x>maxc){
            maxc=v[i].y;
            k++;
        }
    printf("%d",k);
    return 0;
}