def make_divisors(n):
    lower_divisors, upper_divisors = [], []
    i = 1
    while i * i <= n:
        if n % i == 0:
            lower_divisors.append(i)
            if i != n // i:
                upper_divisors.append(n // i)
        i += 1
    return lower_divisors + upper_divisors[::-1]


N = int(input())

divisors = make_divisors(N)

flg = False
for d in divisors:
    a = (N // d + d) / 2
    b = (N // d - d) / 2
    if not (a == int(a) and b == int(b)):
        continue
    if a ** 2 - b ** 2 == N:
        flg = True

print(1 if flg else -1)