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 (Clang 3.8.0) (judge verdict: Accepted)

#include<stdio.h>
#include<math.h>
int main(){
    long int N;
    long int x = 1;
    long int count = 0;
    scanf("%ld",&N);
    while(x*x+x < N){
        if(N%x==0){count += ((N/x)-1);}
        x++;
    }
    printf("%ld\n",count);
}