public class Main {
  public static void mystery(List<String> list) {
      Set<String>Result= new TreeSet<String>();
      for(String element:list){
          if(element.compareTo(list.get(0))<0){
              result.add(element);
          }else{
              result.clear();
          }
      }
   System.out.println(result);
  }
}