def gcd(a, b):
    if b==0:
        return a
    else:
        return gcd(b, a%b)

N = input()
g = N*(N-1)/2
p = gcd(g, N)
i = 1
ans = 0
while i*i <= p:
    if p%i == 0:
        ans += i
        if i*i < p:
            ans += p/i
    i += 1

print ans