using System;
using System.Text;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
using System.Runtime.Serialization.Formatters;
using static System.Console;
using static System.Math;

namespace YukiCoder
{
    public class Program
    {
        public static void Main(string[] args)
        {
            new Program().Solve();
        }

        public void Solve()
        {
            int N = int.Parse(Console.ReadLine());
            int n = 1000;
            bool[] primes = SieveOfEratosthenes(n);
            int sum = 0;

            for (int i = 0; i <= N; i++)
            {
                if (primes[i])
                {
                    sum += i;
                }
            }
            
            WriteLine(sum);

        }
        
         public static bool[] SieveOfEratosthenes(int n)
        {
            bool[] isPrime = new bool[n+1];
            for (int i = 0; i < n; i++)
            {
                isPrime[i] = true;
            }
        
            isPrime[0] = false;
            isPrime[1] = false;
        
            for (int i = 2; i < Math.Sqrt(n); i++)
            {
                int j;
                if (isPrime[i])
                {
                    j = i + i;
                    while (j <= n)
                    {
                        isPrime[j] = false;
                        j = j + i;
                    }
                }
            }

            return isPrime;
        }

    }
}