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

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


bool x[2000001];
long long i,j,n;
int main()
{
    cin>>n;
    if (n==1) cout<<"0";
    else
    {
        for (i=2;i<=10;++i)
        {
            if (!x[i])
            {
                j=1;
                while (i*j<=n)
                {
                    j++;
                    x[i*j]=true;
                }
            }
        }
    }

    int db;
    db=0;
    for (i=2;i<=n;++i) if (x[i]==false) db++;

    cout<<db;
    return 0;
}