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

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object RationalMain {
  def main(args:Array[String]) {
    val x = new Rational(1,3)
    val y = new Rational(2)
    val z = 2.+(x)   //  shows error like cannot be applied to (Rational) 
    println(z)
   
  }
}