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( int argc , char *argv[] )
{
  long long int n;
  long long int i;
  long long int sum = 0;
  
  scanf( "%lld\n" , &n );

  for( i = 2 ; i*i < n ; i++ ) {
    if( n % i == 0 ) {
      if( i != 2 ) {
    	  sum += ( i - 1 );
      }
      sum += ( n / i - 1 );
    }
  }
  
  sum += ( n - 1 );
  
  printf( "%lld\n" , sum );
  
  return 0;
}