def is_square_free(factors):
 '''
 This functions takes a list of prime factors as input.
 returns True if the factors are square free.
 '''
 for i in factors:
 if factors.count(i) > 1:
 return False
 return True


def prime_factors(n):
 '''
 Returns prime factors of n as a list.
 '''
 i = 2
 factors = []
 while i * i <= n:
 if n % i:
 i += 1
 else:
 n //= i
 factors.append(i)
 if n > 1:
 factors.append(n)
 return factors


def mobius_function(n):
 '''
 Defines Mobius function
 '''
 factors = prime_factors(n)
 if is_square_free(factors):
 if len(factors) % 2 == 0:
 return 1
 elif len(factors) % 2 != 0:
 return -1
 else:
 return 0