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: Wrong Answer)

#include <stdio.h>

int main(void){
  long long N;
  scanf("%lld",&N);

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

  printf("%lld\n",ans);

  return 0;
}