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 Fortran (gfortran v4.8.4) (judge verdict: Accepted)

program diverta2019_d
    use,intrinsic :: iso_fortran_env
    implicit none
    integer(int64):: n,i,ans=0

    read*, n
    i=1
    do while(i*i <= n)
        if (mod(n,i) == 0) then
            if (i*(i+1) < n) ans=ans+(n/i-1)
        end if
        i=i+1
    end do
    print'(i0)', ans
end program diverta2019_d