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: Accepted)

#include<stdio.h>
#include<math.h>

int main(){
    long int N;
    long int ans=0;
    long int i;
    long int top, down;
    long int sqr, tmp;

    scanf("%ld", &N);
    sqr = (int)sqrt(N);

    for(i=1; i<=sqr; i++){
        if(N%i == 0){
            if(i-1>0){
                if((N/(i-1)) == N%(i-1)){
                    ans += (i-1);
                }
            } 
            tmp = N/i;
            if(tmp-1>0){
                if((N/(tmp-1)) == N%(tmp-1)){
                    ans += (tmp-1);
                }
            }
        }
    }
    printf("%ld", ans);

    return 0;
}