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 <bits/stdc++.h>
using namespace std;

const int MOD = (int)1e9+7;

int main(){
	long long N;
	cin >> N;

	if(N==1 || N==2){
		cout << 0 << endl;
		return 0;
	}
	
	long long ans=0;
	for(long long i=1;i*(i+2)<=N;i++){
		if(N%i==0){
			ans+=(N/i-1);
		}
	}

	cout << ans << endl;

	return 0;
}