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;
using System.Threading.Tasks;

namespace ConsoleApp99 {
    class Program {
        static void Main(string[] args) {
            //入力
            int N = int.Parse(Console.ReadLine());

            //解答となる数値
            int ans = 0;

            int sho;
            int amari;

            //for (int i = 1; i < N; i++) {
            //    sho = N / i;
            //    amari = N % i;
            //    if (sho == amari) {
            //        ans += i;
            //    }
            //}

            for (int i = 1; i < Math.Sqrt(N); i++) {
                if ((N - i) % i == 0) {
                    if ((N - i) / i > i) {
                        ans += (N - i) / i;
                    }
                }
            }

            //出力
            Console.WriteLine(ans);

        }
    }
}