Book

class Book(var numOfPages: Int, var pagePrice: Int=0, var type: Type = Type.SOFT_COPY) {
    init {
        if(numOfPages<=0)
            throw  RuntimeException("Number of pages must be more than zero")
    }
    fun calculateBookPrice(): Int {
        var price: Int = numOfPages * pagePrice

        if (type == Type.HARD_COPY)
            price += 20
        return price
    }
    fun isACookBook(): Boolean {
        return numOfPages <= 200
    }
}
enum class Type {
    HARD_COPY, SOFT_COPY
}