using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    static int[][] NArr(long n) => Enumerable.Repeat(0, (int)n).Select(_ => NList).ToArray();
    static string[] SList(long n) => Enumerable.Repeat(0, (int)n).Select(_ => ReadLine()).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var n = long.Parse(ReadLine());
        var ans = 0;
        var a = decimal.One;
        for (var i = 2; i < 100; ++i)
        {
            if (IsPrime(i))
            {
                if (n < a * i)
                {
                    WriteLine(ans);
                    return;
                }
                a *= i;
                ++ans;
            }
        }
    }
    static bool IsPrime(int n)
    {
        if (n == 1) return false;
        if (n == 2) return true;
        if (n % 2 == 0) return false;
        int i = 3;
        while (i * i <= n)
        {
            if (n % i == 0) return false;
            i = i + 2;
        }
        return true;
    }
}