public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (sc.hasNext()) {
            int n = Integer.parseInt(sc.next());
            LinkedList<Integer> list = new LinkedList<>();
            int head = Integer.parseInt(sc.next());
            list.add(head);
            for (int i = 1; i < n; i++) {
                int pre = Integer.parseInt(sc.next());
                int cur = Integer.parseInt(sc.next());
                int indexInsert = list.indexOf(cur) + 1;
                list.add(indexInsert, pre);
            }
            int delete = Integer.parseInt(sc.next());
            list.removeIf(integer -> integer.equals(delete));
            if (list.size() == 0) {
                System.out.println("null");
            } else {
                for (Integer integer : list) {
                    System.out.print(integer + " ");
                }
            }
        }
    }
}