#include<iostream>
#include<fstream>
using namespace std;
int main()
{
	ifstream f("ciur.in");
	ofstream g("ciur.out");
int v[200],i,j,n,a=0;
f>>n;v[2]=1;
for(i=3;i<=n;i+=2)
{
	v[i]=1;v[i-1]=0;}
v[2]=1;
for(i=3;i<=n;i+=2)
	if(v[i]!=0)
		for(j=i+2;j<=n;j+=2)
			if(v[j]&&(j%i==0)) v[j]=0;
for(i=3;i<=n;i+=2)
	if(v[i]) a=a+1;
g<<a+1;
return 0;
}