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 (Clang 3.8.0) (judge verdict: Runtime Error)

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

int main(void)
{
	long int n;
	long int i, j, k;
	long int sum = 0;
	
	
	scanf("%ld", &n);
	
	for(i = 1; i <= (int)sqrt(n); i++) {
		if(n % i == 0) {
			if(i > 1) {
				if( (n / (i - 1)) == (n % (i - 1)) ) {
					sum += (i - 1);
				}
			}
			if( (n / (n / i - 1)) == (n % (n / i - 1)) ) {
				sum += (n / i - 1);
			}
		}
	}
	
	if(n % (int)sqrt(n) == 0) {
		if( (n / ((int)sqrt(n) - 1)) == (n % ((int)sqrt(n) - 1)) ) {
			sum -= (int)sqrt(n);
		}
	}
	
	printf("%ld\n", sum);
	
	return 0;
}