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: Wrong Answer)

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include <math.h>

int main(void) {
	long long n;
	long long max;
	long long ans = 0;

	scanf("%lld", &n);
	if (n == 2)printf("0");
	else {
		max = (long long)sqrt(n);
		if (n == max * max)max--;
		//max = 1000000;
		//printf("%lld\n", max);
		for (long long i = 1; i <= max; i++) {
			if (n % i == 0)
				ans += n / i - 1;
		}
		printf("%lld", ans);
	}
	return 0;
}