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<stdlib.h>
#include<math.h>
#include<string.h>

//関数宣言
//int func(int x, int y);

int main(void){

  //スカラー入力
  long long int N;

  scanf("%lld", &N);

  int i_max;
  i_max = floor(sqrt((double) N));
  /* printf("%d\n", i_max); */

  long long int R,m,ans=0;
  for(long long int i=1; i<=i_max; i++){
    R = (N-i)%i;
    if(R==0){
      m = (N-i)/i;
      if(m>i){
        ans = ans+m;
      }
      /* printf("i=%lld, m=%lld\n", i, m); */
    }
  }
  printf("%lld\n", ans);

  return 0;
}