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 Ruby (2.3.3) (judge verdict: Runtime Error)

n = gets.to_i
ans = 0
(1..n**0.5).each do|i|
  if n%i == 0
    if i-1 !=0
      if n % (i-1) == n/(i-1)
        ans += (i - 1)
      end
    end
    if n % (n/i-1) == n/(n/i-1)
       ans += (n/i -1)
    end
  end
end
puts ans