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 main
Implicit None
	integer(8)::n,a=1,p=0
	
	read*,n
	
	do
		if((n/a-1) < a) exit
		if(mod(n,a) == 0)then
			if((n/a-1) > a) p = p + n/a-1
		endif
		a = a+1
	enddo
	print"(i0)",p
end program main