def generate_combinations(n, max_number):
    # Initialize the combination
    combination = [0] * n

    # Generate all combinations
    while True:
        # Print the current combination
        print(combination)

        # Increment the combination
        i = n - 1
        while i >= 0:
            if combination[i] < max_number:
                combination[i] += 1
                break
            else:
                combination[i] = 0
                i -= 1

        # If i < 0, we've exhausted all combinations
        if i < 0:
            break


if __name__ == '__main__':
    # Generate all 8-digit combinations
    generate_combinations(4, 4)