def fibonacci(n: int) -> int:
    """
    The Fibonacci sequence is a list of numbers where the subsequent number is the sum of the previous two.
    :param n: The number of items requested for the Fibonacci sequence.
    :return: The Fibonacci number at position n
    """
    if n <= 0:
        raise ValueError("The number must be greater than zero.")
        exit(code=1)
    if n == 1:
        return 0
    elif n == 2:
        return 1
    else:
        return fibonacci(n-1) + fibonacci(n - 2)