using System;

public class Program

{

    public static void Main()

    {

        int answer = 0;

        int endNum = 1000;

        for(int i = 1; i < endNum; i++)

        {

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

            {

                answer += i;

            }

        }   

        Console.WriteLine(answer);

    }

}