using System;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var numbers = Enumerable.Range(1,999);

        int sum = 0;

        foreach(int number in numbers)

        {

            if(number % 3 == 0 || number % 5 == 0)

            {

                sum = sum + number;

            }

        }

        Console.WriteLine(sum);

    }

}