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 Python (3.4.3) (judge verdict: Wrong Answer)

import sys
import math

def div_list(n):
    i = 2
    res = []
    while i**i <= n:
        if i*i == n:
            res.append(i-1)
            break
        if n % i == 0:
            res.append(int(n/i)-1)
        i += 1
    res.append(n-1)
    return res

N = int(sys.stdin.readline().strip())
num_list = div_list(N)
#print(num_list)

#num_list = list(map(lambda x: x-1, num_list))
print(sum(num_list))