#include<stdio.h>
int main()
{ 
	long int n,i,j,contor=0;
	bool v[2000002];
	freopen("ciur.in", "r", stdin);
	freopen("ciur.out", "w", stdout);
	scanf("%ld",&n);
	for(i=1;i<=n;++i){v[i]=0; contor++;}
	for(i=2;i<=(n/2);i++){
      for(j=2;(j*i)<=n;j++)
        { if(v[j*i]==1)contor++; v[i*j]=1; contor--;}}
	contor++;
	 printf("%ld", contor); return 0;
}