import java.io.*;

class UseIntSets20
{
// Set maintenance program with constructive set class
// Includes 'undo' command with multiple levels of undo

 public static void main(String[] args)
 throws IOException
 {
  int n=0;
  char ch;
  String line;
  BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
  Stack done = new Stack(), undone = new Stack();
  IntSet20 mySet = new IntSet20();
  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' :
            done.push(mySet);
            mySet = mySet.delete(n);
            undone = new Stack();
            break;
          case 'a' :
            done.push(mySet);
            mySet = mySet.add(n);
            undone = new Stack();
            break;
          case 'm' :
            if(mySet.member(n))
               System.out.println("Is a member");
            else
               System.out.println("Not a member");
            break;
          case 'u':
            if(done.isEmpty())
               System.out.println("Nothing to undo");
            else
               {
                undone.push(mySet);
                mySet = (IntSet20) done.top();
                done.pop();
               }
            break;
          case 'r':
            if(undone.isEmpty())
               System.out.println("Nothing to redo");
            else
               {
                done.push(mySet);
                mySet = (IntSet20) undone.top();
                undone.pop();
               }
            break;
          case 'p':
            System.out.println(mySet);
            break;
          default:
            System.out.print("d - delete, a - add, m - member,");
            System.out.println("u - undo,  r - redo, p - print, q - quit");
            break;
         }
     }
  while(ch!='q');
 }

}