def hello(x=None) -> str:
    return f"Hello{', ' + str(x) if x else ''}!"


def int_to_roman(x: int) -> str:
    int_roman = [
        (1000, "M"),
        (900, "CM"),
        (500, "D"),
        (400, "CD"),
        (100, "C"),
        (90, "XC"),
        (50, "L"),
        (40, "XL"),
        (10, "X"),
        (9, "IX"),
        (5, "V"),
        (4, "IV"),
        (1, "I"),
    ]

    res = ""
    for n, rom in int_roman:
        while x >= n:
            res += rom
            x -= n

    return res


def longest_common_prefix(x: list[str]) -> str:
    if not x or not x[0]:
        return ""

    prefix = x[0].strip()
    break_flag = False

    i = 0
    while i < len(prefix):
        for s in x:
            s = s.strip()

            if i >= len(s) or s[i] != prefix[i]:
                break_flag = True

                break

        if break_flag:
            break

        i += 1

    return prefix[:i]


class BankCard:
    def __init__(self, total_sum: int, balance_limit: int = -1) -> None:
        self.total_sum = total_sum
        self.balance_limit = balance_limit

    def put(self, sum_put: int):
        self.total_sum += sum_put
        print(f"You put {sum_put} dollars.")
        return self

    @property
    def balance(self) -> int:
        if self.balance_limit == 0:
            raise ValueError("Balance check limits exceeded.")

        self.balance_limit -= 1
        return self.total_sum

    def __add__(self, other):
        return type(self)(
            self.total_sum + other.total_sum,
            (
                max(self.balance_limit, other.balance_limit)
                if self.balance_limit != -1 and other.balance_limit != -1
                else -1
            ),
        )

    def __str__(self) -> str:
        return "To learn the balance call balance."

    def __call__(self, sum_spent: int) -> None:
        if self.total_sum < sum_spent:
            raise ValueError(f"Not enough money to spend {sum_spent} dollars.")

        print(f"You spent {sum_spent} dollars")
        self.total_sum -= sum_spent

        return


def primes():
    num = 2

    while True:
        prime = True

        for i in range(2, int(num**0.5) + 1):
            if not num % i:
                prime = False

                break

        if prime:
            yield num

        num += 1