static void Main(string[] args)
{
Thermometer thermometer = new Thermometer();
ThermometerDisplay display1 = new ThermometerDisplay(1, thermometer);
ThermometerDisplay display2 = new ThermometerDisplay(2, thermometer);
ThermometerDisplay display3 = new ThermometerDisplay(3, thermometer);
thermometer.AddObserver(display1);
thermometer.AddObserver(display2);
thermometer.AddObserver(display3);
thermometer.ReadTemperature();
thermometer.RemoveObserver(display1);
thermometer.ReadTemperature();
thermometer.AddObserver(display1);
thermometer.ReadTemperature();
thermometer.ReadTemperature();
thermometer.ReadTemperature();
}