program ex(f1,f2);
 const
  yichu='queue out';
  queshao='queue empty';
 type
  zn=array [0..3000] of longint;
 var
  a:zn; f1,f2:text; head,tail:integer; i,j,k,n,m,p:integer;
 begin
  assign(f1,'queue.in'); reset(f1);
  assign(f2,'queue.out'); rewrite(f2);
  readln(f1,n);
  head:=1; tail:=0;
  for i:=1 to n do
   begin
    read(f1,j);
    if j=2 then read(f1,k);
    readln(f1);
    case j of
    1:  begin
          head:=1; tail:=0;
        end;
    2:  if tail+1>10 then writeln(f2,yichu)
                     else begin
                           inc(tail);
                           a[tail]:=k;
                          end;
    3:  if head+1>tail then writeln(f2,queshao)
                       else inc(head);
    4:  begin
          writeln(f2,tail-head+1);
          for p:=head to tail-1 do write(f2,a[p],' ');
          writeln(f2,a[tail]);
        end;
    end;
   end;
  close(f1);
  close(f2);
 end.