class BankAccount:
    def __init__(self, balance: float) -> None:
        self.balance = balance

    def deposit(self, amount: float) -> None:
        self.balance += amount

    def withdraw(self, amount: float) -> None:
        if amount <= self.balance:
            self.balance -= amount


class SavingsAccount(BankAccount):
    def __init__(self, balance: float, interest_rate: float) -> None:
        # Llama al constructor del padre con super() y guarda el interest_rate
        super().__init__(balance)
        self.interest_rate = interest_rate 

    def apply_interest(self) -> None:
        # Incrementa el saldo según la tasa de interés
        self.balance *= (1 + self.interest_rate)


def savings_after_interest(initial: float, rate: float, months: int) -> float:
    # Crea SavingsAccount y aplica el interés months veces; retorna saldo final
    savings = SavingsAccount(initial, rate)
    for i in range(months):
        savings.apply_interest()

    return savings.balance