from math import gcd

n = int(input())
n2 = n * (n - 1) // 2
x = gcd(n, n2)
ans = 0
for i in range(1, int(x ** 0.5) + 1):
    if x % i == 0:
        ans += i
        ans += x // i
        if x == i ** 2:
            ans -= i
print(ans)