//#include <iostream>
#include <fstream>

using namespace std;

ifstream cin("ciur.in");
ofstream cout("ciur.out");

int n,i,p,db,o;
int main()
{
    cin>>n;
    for(i=1;i<=n;++i)
    {
        o=1;
        while(o<=i)
        {
            if(i%o==0) p++;
            o++;
            if(p>2) break;
        }
        if(p==2) db++;
        p=0;
    }
    cout<<db;
    return 0;
}