class TollGate
  def initialize(card)
    @status = 0
  end

  def open_gate
    @status = 1
  end

  def close_gate
    @status = 0
  end
end

class Sensor
  def initialize(card)
    @card = card
  end

  def is_right_card?
    true if @card == 'toll-card'
    false
  end
end

class Checker
  def initialize(balance)
    @balance = balance
  end

  def is_balance_enough?
    true if @balance >= 3000
    false
  end
end