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 Pascal (FPC 2.6.2) (judge verdict: Wrong Answer)

var i : longint;
    n,ans:int64;

begin
  read(n);
  ans := 0;
  for i := 1 to 999999 do begin
    if (i+1)*(i+1)>n then break;
    if n mod i = 0 then
      if n div i - 1 > i then ans := ans + n div i - 1
  end;
  writeln(ans);
end.