/*
 * Einstein -- Performs calculations concerning time dilation.
 *
 * Tell Einstein what fraction of the speed of light you're 
 * traveling to the Andromeda galaxy, and Einstein tells you 
 * how long the trip will appear to you, taking relativistic 
 * effects (i.e., time dilation) into account.
 */
class Einstein {
   static public void main(String[] args) {
      Galaxy     destination = new Andromeda();
      double     distanceLightYears = destination.getDistance();
      SpaceShip  enterprise;
      double     time;

      showInstructions();
      try {
         enterprise = new SpaceShip(getPercentC());
         time = enterprise.calcTimeDilation(distanceLightYears);
         showResults(time);
         showBackOnEarth(distanceLightYears, enterprise.speed);
      } catch (WarpException e) {
         System.out.println("Sorry, dilithium crystals have not been
invented yet.");
      } catch (Exception e) {
      }
   }


   /** Tell the user how this program works.
     */
   static void showInstructions() {
      System.out.println("Enter your speed as a percentage of the speed of ");
      System.out.println("light. I will calculate the time required for you
to travel ");
      System.out.println("to the Andromeda galaxy, 2.2 million light years
away.");
      System.out.println("");
   }

   /** Get input from the user.
     */
   static double getPercentC()
         throws java.io.IOException {
      StringBuffer buffer = new StringBuffer();
      char         c;     

      while ((c = (char)System.in.read()) != '\n')
         buffer.append(c);

      return Double.valueOf(buffer.toString()).doubleValue();
   }

   /** Tell the user the results of the calculation.
     */
   static void showResults(double time) {
      int years = getYears(time);
      int days = getDays(time);
      System.out.println("Travel time as you perceive it, ");
      System.out.println("with relativistic effects, is: ");
      System.out.println(years + " years and " + days + " days.");
      System.out.println("");
   }

   /** Show what's happening back on earth.
     */
   static void showBackOnEarth(double distanceLightYears, double speed) {
      double distanceKm = Light.lightYearToKm(distanceLightYears);
      double elapsed = distanceKm/speed;
      System.out.println("Back on earth, " + getYears(elapsed) + " years and ");
      System.out.println(getDays(elapsed) + " days would have elapsed.");
      System.out.println("");
   }

   private static int getYears(double time) {
      return (int)time;  // integer portion
   }

   private static int getDays(double time) {
      return (int)((time - (double)(int)time)* 365.0); 
   }

}

/** Light keeps track of C and has utilities to perform conversions.
  */
class Light {
   public static final double Cm_s = 2.998E8;       // meters/second
   public static final double Ckm_yr = 94544.928E8; // kilometers/year

   public static final double lightYearToKm(double lightYear) {
      return lightYear * Ckm_yr;
   }
}

/** SpaceShips instances maintain a speed and know about
  * time dilation.
  */
class SpaceShip {
   double fraction;     // fraction of the speed of light
   double speed;        // speed in km/yr

   SpaceShip(double percent) {
      fraction = percent/100.0;
      speed = fraction * Light.Ckm_yr;
   }

   /** Determine the time required to travel a distance in the
     * moving time frame, given the speed maintained by this object.
     */
   double calcTimeDilation(double distanceLightYr)
      throws WarpException {

      double distanceKm = Light.lightYearToKm(distanceLightYr);

      if (fraction > 1.0)
         throw new WarpException();

      return (distanceKm/speed) * Math.sqrt(1.0 - (fraction*fraction));
   }

}

abstract class Galaxy {
   abstract public double getDistance();
}

class Andromeda extends Galaxy {
   public double getDistance() {
      return 2.2E6; // in light-years
   }
}

class WarpException extends Exception {
}