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;

namespace D2019PC
{
    class C
    {
        static void Main(string[] args)
        {

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

            List<long> list = new List<long>();
            for (long i = 1; i < Math.Sqrt(N); i++)
            {
                if (N % i == 0)
                {
                    list.Add((N / i) - 1);
                }
            }

            long count = 0;
            foreach (var i in list)
            {
                if (N % i != 0) count += i;
            }
            Console.WriteLine(count);
        }
    }
}