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# (Mono 4.6.2.0) (judge verdict: Accepted)

namespace inonoa{
    class Ino{
        static void Main(){
            long n = long.Parse(System.Console.ReadLine());
            long ans = 0;
            long mn = (long)System.Math.Sqrt(n);
            for(long i=1;i<=mn;i++){
                if(n%i==0){
                  long m = n/i -1;
                  if(m!=0){if(n%m==n/m){ans += m;}}
                  if(i-1!=0){if(n%(i-1)==n/(i-1)){ans += i-1;}}
                }
            }
            System.Console.WriteLine(ans);
        }
    }
}