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 <iostream>
#include <math.h>
using namespace std;
int main(void){
long long ans = 0;
long long n;
cin >> n;
long long fav;
long long k;
k = sqrt(n);
for(long long i=1;i<=k;i++){
    if((n-i) % i == 0){
        fav = (n-i) / i;
        if (n / fav == n % fav){
        ans += fav;
        //cout << ans << " " << fav << " " << i <<  endl;
        //cout << n / fav << " " << n % fav << endl;
        }
    }
}
cout << ans << endl;
}