ltime = System.currentTimeMillis();
                    wait();
                }

                try {
                    double r = Math.random();
                    if (r < 0.333) {
                        f.exists();
//                      System.out.print('e');
                    } else if (r < 0.667) {
                        d.listFiles();
//                      System.out.print('l');