Problem:
Score : 500 points

Problem Statement

Snuke received a positive integer N from Takahashi.
A positive integer m is called a favorite number when the following condition is satisfied:

The quotient and remainder of N divided by m are equal, that is, \lfloor \frac{N}{m} \rfloor = N \bmod m holds.

Find all favorite numbers and print the sum of those.

Constraints

All values in input are integers.

1 \leq N \leq 10^{12}

Input

Input is given from Standard Input in the following format:

N

Output

Print the answer.

Sample Input 1

8

Sample Output 1

10

There are two favorite numbers: 3 and 7. Print the sum of these, 10.

Sample Input 2

1000000000000

Sample Output 2

2499686339916

Watch out for overflow.

Solution in C# (Mono 4.6.2.0) (judge verdict: Runtime Error)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
using static System.Math;

namespace AtCorder
{
    class Program
    {
        public static void Main(string[] args)
        {
            var n = long.Parse(Console.ReadLine());

            long i = n - 1;
            long count = 0;
            while (true)
            {
                var div = n / i;
                var mod = n % i;
                if (div == mod)
                {
                    count += i;

                    i = n / (div + 1) - 1;
                }
                else if (mod > div)
                {
                    i = n / (div + 1) - 1;
                }
                else
                {
                    i--;
                }

                if (i <= 0)
                {
                    break;
                }
            }

            Console.WriteLine(count);
        }
    }
}