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 Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.util.*;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        long n = sc.nextLong();
        long sum = 0;

        List<Long> list = divisor(n);
        for(long i : list){
            i--;
            if(i == 0){
                continue;
            }
            if(n / i == n % i){
                sum += i;
            }
        }

        System.out.println(sum);

    }

    public static ArrayList<Long> divisor(long n){
        ArrayList<Long> result = new ArrayList<>();
        for(long i = 1; i * i <= n; i++){
            if(n % i == 0){
                result.add(i);
                if(i != n / i){
                    result.add(n / i);
                }
            }
        }
        return result;
    }

}