LISP calc #1

; calculator function definition
(defun calculator ()
; variable firnum as an input
(princ "Enter the first number: ")
(setq firnum (read))
; variable secnum as an input
(princ "Enter the second number: ")
(setq secnum (read))
; variable sumnum as a result of firnum + secnum
(setq sumnum (+ firnum secnum))
; formated output with firnum and secnum as a text and sumnum as a decimal
(format t "Sum of ~r and ~r is: ~D" firnum secnum sumnum))
; calculator function
(calculator)