using System;
using System.Collections;

class main
{
    static void Main(String[] args)
    {
        while (true)
        {
            string s = Console.ReadLine();           
            if (s != null)
            {
                int c = 0;
                int f = 0;
                int n = int.Parse(s);
                int r = (int)Math.Sqrt(n);
                ArrayList  p = new ArrayList();
                if (n > 1)
                {
                    for (int a = 2; a <= n; a++)
                    {
                        p.Add(a);
                    }
                    while (true)
                    {
                        f = (int)p[0];
                        c++;
                        for (int i = 0; i < n; i++)
                        {
                            p.Remove(f * i);
                        }
                        if (f > r)
                        {
                            break;
                        }
                    }
                    Console.WriteLine("{0}",c+p.Count);
                }
                if (n <= 1)
                {
                    Console.WriteLine(0);
                }
            }
            if (s == null)
            {
                break;
            }
        }
        Console.ReadKey();
    }
}