(budget, exchange_rate, spread, denomination)
return non_exchangeable_amount
:param budget: float - amount of money you are planning to exchange.
    :param exchange_rate: float - unit value of the foreign currency.
    :param spread: int - the percentage taken as an exchange fee.
    :param denomination:  int - the value of a single bill.
    :return: int - the value that cannot be exchanged, due to the denomination.
def non_exchangeable_value(budget, exchange_rate, spread, denomination):
    """

    :param budget: float - amount of money you are planning to exchange.
    :param exchange_rate: float - unit value of the foreign currency.
    :param spread: int - the percentage taken as an exchange fee.
    :param denomination:  int - the value of a single bill.
    :return: int - the value that cannot be exchanged, due to the denomination.
    """

    exchange_fee = (exchange_rate / 100) * spread
    actual_rate = exchange_rate + exchange_fee
    non_exchangeable_amount = int((budget / actual_rate) % denomination)
    return non_exchangeable_amount
def non_exchangeable_value ( budget , exchange_rate , spread , denomination ) : exchange_fee = ( exchange_rate / 100 ) * spread actual_rate = exchange_rate + exchange_fee non_exchangeable_amount = int ( ( budget / actual_rate ) % denomination ) return non_exchangeable_amount