#include<stdio.h>
#include<string.h>
FILE*fin,*fout;
int v[1000001],i,j,n,m,d,nr,t;
int  main(){
fin=fopen("fractii.in","r");
fout=fopen("fractii.out","w");
fscanf(fin,"%d",&n);
int n1;
for(j=1;j<=n;j++){
	d=2;n1=j;
while(d*d<=n1){
	t=0;
   while(n1%d==0){
   t++;
   n1=n1/d;
   }
if(t!=0)
for(i=d;i<=n;i=i+d){v[i]=1;}


if(d==2){d++;}
else{d=d+2;}

}

if(n1!=0&&n1!=1)
for(i=n1;i<=n;i=i+n1){v[i]=1;}

//v[1]=1;



for(i=1;i<=n;i++)
if(v[i]==0){nr++;}
//memset(v,n,0);
for(i=1;i<=n;i++){v[i]=0;}
}








fprintf(fout,"%d",nr);
return 0;}