using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("\nSum of the first 500 prime numbers: ");

           long sum = 0;

            int ctr = 0;

            int n = 2;

            while (ctr < 500)

              {

                if (isPrime(n))

                {

                    sum += n;

                    ctr++;

                }

                n++;

            }

​

            Console.WriteLine(sum.ToString());

    }

     public static bool isPrime(int n)

        {

            int x = (int)Math.Floor(Math.Sqrt(n));

​

            if (n == 1) return false;

            if (n == 2) return true;

​

            for (int i = 2; i <= x; ++i)

            {

                if (n % i == 0) return false;

            }

​

            return true;

​

    }

}