(budget, exchange_rate, spread, denomination)
return exchangeable_amount * denomination
:param budget: float - the amount of your money you are planning to exchange.
    :param exchange_rate: float - the unit value of the foreign currency.
    :param spread: int - percentage that is taken as an exchange fee.
    :param denomination: int - the value of a single bill.
    :return: int - maximum value you can get.
def exchangeable_value(budget, exchange_rate, spread, denomination):
    """

    :param budget: float - the amount of your money you are planning to exchange.
    :param exchange_rate: float - the unit value of the foreign currency.
    :param spread: int - percentage that is taken as an exchange fee.
    :param denomination: int - the value of a single bill.
    :return: int - maximum value you can get.
    """

    exchange_fee = (exchange_rate / 100) * spread
    actual_rate = exchange_rate + exchange_fee
    exchangeable_amount = int((budget / actual_rate) / denomination)
    return exchangeable_amount * denomination
def exchangeable_value ( budget , exchange_rate , spread , denomination ) : exchange_fee = ( exchange_rate / 100 ) * spread actual_rate = exchange_rate + exchange_fee exchangeable_amount = int ( ( budget / actual_rate ) / denomination ) return exchangeable_amount * denomination