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 (GCC 5.4.1) (judge verdict: Accepted)

#include <stdio.h>
long long n;

int main()
{
	long long ans = 0;
	scanf("%lld", &n);

	for (long long i = 1; i*i <= n; i++)
	{
		if (n % i == 0)
		{
			long long t = n / i;
			long long m = t - 1;
			if(i < m)
				ans += m;
		}
	}

	printf("%lld", ans);


	return 0;
}