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>

int main()
{
	long long int   N, n, S, A, r;   // 整数
	int   ns = 2;   // 素因数
	int   j;      // 乗数
	int	  x, k;

	scanf("%lld", &N);   // 整数を入力

	S = 1;
	x = 1;
	A = 1;
	r = 1;

	for (n = N, ns = 2; n >= ns; ns++)
	{
		
		for (j = 0; n%ns == 0; j++)            // 割り切れる間繰り返す
		{
			n /= ns;
			r *= ns;
			S += r;
		}


		if (j == 0) continue;               // 1回も割り切れなかった
		A *= S;
		x *= j + 1;
		S = 1;
	}
	printf("%lld", A - x - 1);

	return 0;
}