import java.util.HashSet;
import java.util.Scanner;

public class ParkingLot {
    public static void main(String[] args) {
        Scanner scanner=new Scanner(System.in);

        String input = scanner.nextLine();

        HashSet<String> paking = new HashSet<>();

        while (!input.equalsIgnoreCase("end")){
            String[] splitInput = input.split(", ");

            switch (splitInput[0]){
                case "IN":paking.add(splitInput[1]);
                break;
                case "OUT":paking.remove(splitInput[1]);
                break;
                default:return;
            }

            input=scanner.nextLine();
        }

        if (paking.isEmpty())
            System.out.println("Parking Lot is Empty");
        else{
            paking.forEach(carNum-> System.out.println(carNum));
        }
    }
}