Program P55;
type Semnal=(Rosu, Galben, Verde);
var s : Semnal;
begin
 s:=Verde;
 s:=pred(s);
 case s of
          Rosu : writeln('STOP');
        Galben : writeln('ATENŢIE');
         Verde : writeln('START');
 end;
 readln;
end.