public static int commonPassengersCount( PassengerTrain train ){
		int res = 0;
		for ( RailwayVehicle it : train ){
			if ( it instanceof PassengerCar ){
				PassengerCar pCar = (PassengerCar)it;
				res+= pCar.getPassengersCount();
			}
		}
		return res;
	}