class Rational(n: Int, d: Int) {
  val numer: Int = n
  val denom: Int = d
 
  def + (that: Rational): Rational =
    new Rational(numer * that.denom + that.numer*denom,
             denom * that.denom)
  def - (that: Rational): Rational =
    new Rational(numer * that.denom - that.numer * denom,
             denom * that.denom)
                
  def + (that: Int): Rational =
     new Rational(numer * 1 + that * denom,
                  denom)
                 
  implicit def intToRational(x: Int) = new Rational(x, 1)
 
 
 
  override def toString() = numer+"/"+denom
}

// test code
     val x = new Rational(1, 2)
      println(x)
     
      val y = x + 1
      println(y)
     
      val z = 1 + x