(defun fn (n)
    (cond
	    ((< n 1) 0)
	    ((eql n 1) 1)
	    ((eql n 2) 1)
       (t (+ (fn (- n 1)) (fn (- n 2))))
    )
)

(defun testfn ()
(print "fn 0 = ")
(print (fn 0))
(print "fn 1 = ")
(print (fn 1))
(print "fn 2 = ")
(print (fn 2))
(print "fn 3 = ")
(print (fn 3))
(print "fn 10 = ")
(print (fn 10))
)


(defun testfn2 ()
(and
(eql (fn 0) 0)
(eql (fn 1) 1)
(eql (fn 2) 1)
(eql (fn 3) 2)
))