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: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;

namespace B
{
    internal static class Program
    {
        private static void Main(string[] args)
        {
            var n = Cint();
            var sum = 0L;

            for (var i = 1; i <= n; ++i)
            {
                if (i % 3 != 0 && i % 5 != 0)
                {
                    sum += i;
                }
            }
            
            Cout(sum);
        }

        #region Input and Output

        private static readonly List<string> Buffer = new List<string>();

        private static string Cin()
        {
            ReadBuffer();

            var str = Buffer.First();
            Buffer.RemoveAt(0);

            return str;
        }

        private static IEnumerable<string> CinA() => Console.ReadLine()?.Split();
        private static int Cint() => int.Parse(Cin());
        private static int[] CintA() => CinA().Select(int.Parse).ToArray();
        private static void Cout(object obj) => Console.WriteLine(obj);

        private static void ReadBuffer()
        {
            if (Buffer.Any()) return;

            var line = Console.ReadLine();
            if (line != null && line.Contains(' '))
            {
                Buffer.AddRange(line.Split());
            }
            else
            {
                Buffer.Add(line);
            }
        }

        #endregion

        #region Loops

        private static void Loop(int count, Action<int> action) => Loop(0, count, action);

        private static void Loop(int init, int count, Action<int> action, int step = 1)
        {
            for (var i = init; i < count + init; i += step)
            {
                action(i);
            }
        }

        #endregion
    }
}