import java.io.*;

class UseIntSequences
{
// Sequence maintenance program

 public static void main(String[] args)
 throws IOException
 {
  int n=0;
  char ch;
  String line;
  BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
  IntSequence mySequence = new IntSequence();
  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' :
            mySequence.delete();
            break;
          case 'a' :
            mySequence.add(n);
            break;
          case 'f' :
            mySequence.forward();
            break;
          case 'b' :
            mySequence.backward();
            break;
          case 'p':
            System.out.println(mySequence);
            break;
          default:
            System.out.print("d - delete, a - add, f - forward,");
            System.out.println(" b - backward, p - print, q - quit");
            break;
         }
     }
  while(ch!='q');
 }

}