Define a class AUTHOR with the following specifications:
Private members of the class BOOK are:
BOOK NO integer type
BOOKTITLE 20 characters
PRICE float (price per copy)
INPUT() : function to read BOOK_NO,BOOKTITLE, PRICE
PURCHASE(): function to ask the user to input the number of copies to be purchased.
TOTAL_COST() : A function to calculate the total cost for N number of copies where N is passed to the function as argument.