public class Stopwatch {
    private long start;
    private long stop;
    
    public void start() {
        start = System.currentTimeMillis(); // start timing
    	//start = System.nanoTime(); // start timing
    }
    
    public void stop() {
        stop = System.currentTimeMillis(); // stop timing
        //stop = System.nanoTime(); // stop timing
    }
    
    public long elapsedTimeMillis() {
        return stop - start;
    }
    
    public String toString() {
        return "elapsed time in milliseconds: " + Long.toString(elapsedTimeMillis()); // print execution time
    }

   /* example */
   public static void main(String[] args) {
      Stopwatch stopwatch = new Stopwatch();
      stopwatch.start();
      long f = fib(10);
      stopwatch.stop();
      System.out.println("fib(10) = " + f + "  " + stopwatch);

      stopwatch.start();
      f = fib(30);
      stopwatch.stop();
      System.out.println("fib(30) = " + f + "  " + stopwatch);

      stopwatch.start();
      f = fib(40);
      stopwatch.stop();
      System.out.println("fib(40) = " + f + "  " + stopwatch);

      stopwatch.start();
      f = fib(41);
      stopwatch.stop();
      System.out.println("fib(40) = " + f + "  " + stopwatch);

      stopwatch.start();
      f = fib(42);
      stopwatch.stop();
      System.out.println("fib(40) = " + f + "  " + stopwatch);
      
   }
    
   public static final long fib(int n) {
      if (n <= 2)
         return 1;
      else
         return fib(n - 1) + fib(n - 2);
   }
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   

}