Program queue;

Type
sc=array [1..10] of integer;

Var
s:sc;
l,n,i,j:integer;
o,oo:integer;
f1,f2:text;

Begin
assign(f1,'queue.in');
assign(f2,'queue.out');
reset(f1);
rewrite(f2);
for i:=1 to 10 do s[i]:=0;
readln(f1,n);
for i:=1 to n do begin
 read(f1,o);
 if o=2 then readln(f1,oo)
 else readln(f1);
 case o of
  1:begin
     for j:=1 to 10 do s[j]:=0;
     l:=0;
    end;
  2:begin
     if l<10 then begin
      s[l+1]:=oo;
      l:=l+1;
     end
     else writeln(f2,'queue out');
    end;
  3:begin
     if l<>0 then begin
      s[1]:=0;
      for j:=2 to l do
       s[j-1]:=s[j];
      l:=l-1;
     end
     else writeln(f2,'queue empty');
    end;
  4:begin
     writeln(f2,l);
     for j:=1 to l do write(f2,s[j],' ');
     writeln(f2);
    end;
 end;
end;
close(f1);
close(f2);
End.