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;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace diverta_D
{
    class Program
    {
        static void Main(string[] args)
        { 
            var n = long.Parse(Console.ReadLine());
            long otpt = 0;
            var z = Math.Sqrt((n));
            long m = (long)(Math.Ceiling(z));
            bool finish = false;
            int i = 0;
            do
            {
                i++;
                if (n%i==0)
                {
                    if (n / i > m)
                    {
                        otpt = otpt + n/i-1;
                    }
                }
                if (i > m)
                {
                    finish = true;
                }
            }
            while (finish == false) ;
            Console.WriteLine(Convert.ToString(otpt));
            Console.ReadKey();
        }
    }
}