def decrementBoats(size:Int):List[Tuple2[Int, Int]] = {
    var boats2 = List[Tuple2[Int, Int]]()
    for(boat <- boats){
      if(boat._2 == size){
        boats2 = boats2 :+ (boat._1 - 1, boat._2)
      } else {
        boats2 = boats2 :+ (boat._1, boat._2)
      }
    }

    boats2
  }

  println(decrementBoats(2))