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: Accepted)

#include<iostream>
#include <math.h>
using namespace std;
 
int main()
{
    long long n;
    cin>>n;
    long long k=0;
    long long l=(long long)sqrt(n);
    if(n<=2){
      cout<<0;
      return 0;
    }
    for(long long m=1;m<=l;m++){
        if(n%m==0){
        	long long x=n/m;
            if(n%(x-1)!=0 && x*x!=n)k+=x-1;
        }
    	//if(n%m!=0 && n%(m+1)==0)k+=m;
    }
    
    cout <<k << endl;
    return 0;
}