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: Accepted)

using System;
using System.Collections.Generic;

public class CSharp
{
    public static void Main()
    {
        Kyopuro chokudai = new Kyopuro();
        chokudai.AtCoder();
    }
}

public class Kyopuro
{
    public void AtCoder()
    {
        string[] input;
        input = Console.ReadLine().Split(' ');

        long n;
        n = long.Parse(input[0]);
        long ans = 0;

        for (long i = 1; i * i < n; i++)
        {
            if (n % i == 0 && n / i - 1 > i) ans += n / i - 1;
        }

        Console.WriteLine(ans);

    }
    public static void DebugWL(object x) { System.Diagnostics.Debug.WriteLine(x); }
}