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++14 (GCC 5.4.1) (judge verdict: Runtime Error)

#include <bits/stdc++.h>
using namespace std;
long long n,ans;
int main(){
	//freopen("input.txt","r",stdin);
	scanf("%lld",&n);
	long long to = sqrt(n);
	while((to + 1)*(to + 1) <= n)to++;
	for(int i = 1;i <= to;i++)
		if((n - i)%i == 0 && n%((n - i)/i) == i)ans+=(n - i)/i;
	printf("%lld\n",ans);
}