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: Wrong Answer)

#include<stdio.h>

int main(void)
{
  long long i,j,N,sum=0;

  scanf("%lld",&N);

  for (i = 1; i*i <= N; i++)
  {

    if((N-1)%i==0)
    {
      j=(N-i)/i;
      if(j&&N/j==N%j)sum+=j;
    }
    if(N/i==N%i)
      sum+=i;
  }

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

  return 0;
}