def divisorGenerator(n, maximum):
    divisors = [1]
    for i in range(1, min(n+1, maximum+1)):
        if n % i == 0 and i not in divisors:
            divisors.append(i)
    return divisors


def greatest_common_divisor(*numbers):
    divisors = []
    numbers = list(numbers)
    numbers.sort()
    maximum = min(numbers[0], round(numbers[-1:][0] / 2))
    number_of_numbers = len(numbers)
    for number in numbers:
        divisors += divisorGenerator(number, maximum)
    divisors.sort()
    divisors.reverse()
    for divisor in divisors:
        if divisors.count(divisor) == number_of_numbers:
            return divisor


if __name__ == '__main__':
    # These "asserts" using only for self-checking and not necessary for auto-testing
    assert greatest_common_divisor(6, 4) == 2, "Simple"
    assert greatest_common_divisor(2, 4, 8) == 2, "Three arguments"
    assert greatest_common_divisor(2, 3, 5, 7, 11) == 1, "Prime numbers"
    assert greatest_common_divisor(3, 9, 3, 9) == 3, "Repeating arguments"
    assert greatest_common_divisor(1, 1) == 1, "1"
    assert greatest_common_divisor(4294967296, 2) == 2, "Edge2"