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: Runtime Error)

#include <stdio.h>

int main(void){
  unsigned long long int N;
  unsigned long long int souwa = 0;
  unsigned long long int i;
  unsigned long long int m;

  scanf("%lld",&N);

  for(i=2;i<=N;i++){
    if(N%i == 0) {
      m = N/i - 1;
      if(N/m == 0)break;
        souwa += m;
      }
  }

  printf("%llu\n",souwa);

  return 0;
}