import java.io.*;

class UseIntSets8c
{
// Set maintenance program, includes 'undo' command
// Uses set class with copy method, implemented with linked lists
// Sets implemented with IntSet11c

 public static void main(String[] args)
 throws IOException
 {
  int n=0;
  char ch;
  String line;
  BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
  IntSet11c mySet = new IntSet11c(),oldSet = new IntSet11c(),tempSet;
  do {
      System.out.print(": ");
      line = in.readLine();
      ch = line.charAt(0);
      if(line.length()>1)
         n = Integer.parseInt(line.substring(1).trim());
      switch(ch)
         {
          case 'q' : 
            break;
          case 'd' :
            oldSet = mySet.copy();
            mySet.delete(n);
            break;
          case 'a' :
            oldSet = mySet.copy();
            mySet.add(n);
            break;
          case 'm' :
            if(mySet.member(n))
               System.out.println("Is a member");
            else
               System.out.println("Not a member");
            break;
          case 'u':
            tempSet = mySet;
            mySet = oldSet;
            oldSet = tempSet;
            break;
          case 'p':
            System.out.println(mySet);
            break;
          default:
            System.out.print("d - delete, a - add, m - member,");
            System.out.println("u - undo,  p - print, q - quit");
            break;
         }
     }
  while(ch!='q');
 }

}