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: Wrong Answer)

using System;

namespace ConsoleApp23
{
    class Program
    {
        static void Main(string[] args)
        {


            long x = long.Parse(Console.ReadLine()) ;

            long N = (long)System.Math.Sqrt(x);

            long Ans = 0;

            //Console.WriteLine(N);

            if (N * N == x)
            {
                for (int n = 1; n < N; ++n)
                {

                    if (x % n == 0)
                    {

                        Ans += x / n - 1;

                        //Console.WriteLine(n-1);
                    }
                }
            }
            else
            {
                for (int n = 1; n <= N; ++n)
                {

                    if (x % n == 0)
                    {

                        Ans += x / n - 1;

                        //Console.WriteLine(n-1);
                    }
                }
            }
            Console.WriteLine(Ans);
        }
    }
}