#include <iostream>

using namespace std;

int main()
{
    int i,j,cnt=-1,n;
    int a[100000];
    cin>>n;
    for (i = 2; i <= n; ++i)
    {

        a[i] = 1;
    }
    for (i = 2; i <= n; ++i)
        if (a[i])
        {
            for (j = i*i; j <= 10; j += i)
            {
                a[j] = 0;
                cnt++;
            }

        }
    cout<<cnt;
    return 0;
}