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: Accepted)

N = int(input())

l = []
for i in range(1, int(N**0.5)+1):
    if N%i==0:
        l.append(i)
        if i!=N//i:
            l.append(N//i)

ans = 0
for i in l:
    m = (N//i)-1
    if m:
        a, b = divmod(N, m)
        if a==b:
            ans += m

print(ans)