public class test{
    public static void main(String[] args){

    System.out.println(notString("not bad"));
    }
    public static String notString(String str) {

          if(str.length() < 3){
            return "not " + str;
          }

          String first3 = str.substring(0,3);
          System.out.println(first3);
          System.out.println(first3.length());
          System.out.println(first3 == "not");
          if(first3 == "not"){
            return str;
          }
          else {
              return "not " + str;
              }


        }

}