#include <fstream>

using namespace std;

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

int main()
{
    int n,i,x=0,xn=0,j=0,contor=0;
    in>>n;
    for (i=1;i<n;i++)
    {
        x=i;
        for (j=1;j<=x;j++)
        {
            if (x%j==0)
            {
                contor++;
            }
        }
        if (contor<=2)
        {
            xn++;
        }
        contor=0;
    }
    out<<xn-1;
    return 0;
}