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)

# def gcd(a_gcd, b_gcd):
#     while b_gcd != 0:
#         a_gcd, b_gcd = b_gcd, a_gcd % b_gcd
#     return a_gcd
#
#
# def lcm(a_lcm, b_lcm):
#     return a_lcm * b // gcd(a_lcm, b_lcm)
#
#
# def max_sum(N_max_sum, a_max_sum):
#     dp = [0] * (N_max_sum + 1)
#     for i in range(N_max_sum):
#         dp[i + 1] = max(dp[i], dp[i] + a_max_sum[i])
#     return dp[N]
#
#
# def knapsack(N_knapsack, W, weight, value):
#     inf = float("inf")
#     dp = [[-inf for _ in range(W+1)] for j in range(N_knapsack + 1)]
#     for i in range(W+1):
#         dp[0][i] = 0
#
#     for i in range(N_knapsack):
#         for w in range(W+1):
#             if weight[i] <= w:
#                 dp[i+1][w] = max(dp[i][w-weight[i]]+value[i], dp[i][w])
#             else:
#                 dp[i+1][w] = dp[i][w]
#     return dp[N_knapsack][W]


def fav(n, i_fav):
    # print((n - i_fav) // i_fav)
    # print((n - 1) / i_fav)
    x = ((n - i_fav) / i_fav)
    if x.is_integer():
        return int(x)
    else:
        return -1


N = int(input())
ans = 0


for i in range(1, N):
    tmp = fav(N, i)
    # print(tmp)
    if tmp == -1:
        continue
    else:
        ans += tmp

print(ans)