Problem:
Score : 200 points

Problem Statement

Let us define the FizzBuzz sequence a_1,a_2,... as follows:

If both 3 and 5 divides i, a_i=\mbox{FizzBuzz}.

If the above does not hold but 3 divides i, a_i=\mbox{Fizz}.

If none of the above holds but 5 divides i, a_i=\mbox{Buzz}.

If none of the above holds, a_i=i.

Find the sum of all numbers among the first N terms of the FizzBuzz sequence.

Constraints

1 \leq N \leq 10^6

Input

Input is given from Standard Input in the following format:

N

Output

Print the sum of all numbers among the first N terms of the FizzBuzz sequence.

Sample Input 1

15

Sample Output 1

60

The first 15 terms of the FizzBuzz sequence are:

1,2,\mbox{Fizz},4,\mbox{Buzz},\mbox{Fizz},7,8,\mbox{Fizz},\mbox{Buzz},11,\mbox{Fizz},13,14,\mbox{FizzBuzz}

Among them, numbers are 1,2,4,7,8,11,13,14, and the sum of them is 60.

Sample Input 2

1000000

Sample Output 2

266666333332

Watch out for overflow.

Solution in C# (.NET Core 3.1.201) (judge verdict: Wrong Answer)

using System;
using System.Collections.Generic;
using System.Data;
using System.Diagnostics;
using System.Globalization;

namespace Csharponly
{
    class Program
    {
        static public void Main()
        {

            int N = oneint();

            double sumN = (1 + N) * N / 2;
            double threeN = ((1 + (N / 3)) * (N / 3) / 2) * 3;
            double fiveN = ((1 + (N / 5)) * (N / 5) / 2) * 5;
            double threefiveN = ((1 + (N / 15)) * (N / 15) / 2) * 15;

            double ans = sumN - (threeN + fiveN - threefiveN);


            Console.WriteLine(ans);

        }
    



        //一つの文字列を受け渡す
        static string onestring()
        {
            return Console.ReadLine();
        }

        //複数の文字列を配列で受け渡す
        //文字列と文字列の間は" "で区切る
        static string[] arraystring()
        {
            return Console.ReadLine().Split(' ');
        }

        //一つの数字を受け渡す
        static int oneint()
        {
            return int.Parse(Console.ReadLine());
        }

        //複数の数字を配列で受け渡す
        //数字と数字の間は" "で区切る
        static int[] arrayint()
        {
            String[] input_line = Console.ReadLine().Split(' ');
            int[] input_num = new int[input_line.Length];
            for (int i = 0; i < input_line.Length; i++)
            {
                input_num[i] = int.Parse(input_line[i]);
            }
            return input_num;
        }
    }
}