function func(var ch: string): string;
const
  ss: array[1 .. 4] of string =
    ('nord','west','east','south');
var
  s: string;
  error, found: boolean;
  i, j: integer;
begin
  s := '';
  error := false;

  if length(ch) > 2 then error := true
  else
    for i := 1 to length(ch) do
      if pos(ch[i], copy(ch, 1, i - 1)) > 0 then error := true
      else begin
        found := false;
        for j := 1 to 4 do begin
          if ch[i] = copy(ss[j], 1, 1) then begin
            s := s + ' ' + ss[j]; found := true;
          end;
        end;
        if not found then error := true;
      end;

  if error then func := 'error !' else func := s;
end;

var
 ch : string;

begin
 write('s = '); readln(ch);
 writeln(func(ch));
end.