(DEFUN QTAK (U) 
       (COND ((EQUAL (CAR U) 1.) (CADR U))
	     (T ((LAMBDA (W) ((LAMBDA (X Y Z) 
			       (COND
				((NOT (LESSP Y X)) Y)
				(T (QTAK (LIST 2.
					       (LIST 2.
						     (LIST 1.
							   (SUB1 X))
						     (LIST 1. Y)
						     Z)
					       (LIST 2.
						     (LIST 1.
							   (SUB1 Y))
						     Z
						     (LIST 1. X))
					       (LIST 3.
						     (LIST 1. X)
						     (LIST 1. Y)
						     Z))))))
			      (CAR W)
			      (CADR W)
			      (CADDR W)))
		 (COND ((EQUAL (CAR U) 2.)
			(LIST (QTAK (CADR U))
			      (QTAK (CADDR U))
			      (CADDDR U)))
		       (T (LIST (SUB1 (QTAK (CADDDR U)))
				(QTAK (CADR U))
				(CADDR U)))))))) 

(DEFUN QQTAK (X Z) 
       (QTAK (LIST 2. (LIST 1. X) (LIST 1. 0.) (LIST 1. Z))))