public class Test {

  public static void main (String[] args) {
    Rational rat1 = new Rational ();
    rat1.num = 6;
    rat1.den = 8;

    Rational rat2 = new Rational (5, 6);

    rat1.print ();
    rat2.print ();

    Rational.negate (rat1);
    rat1.print ();

    Rational.invert (rat2);
    rat2.print ();
    
    Rational result = Rational.add (rat1, rat2);
    result.print ();
  }
}