Project Euler Problem 18 Common Lisp

Project Euler Problem 18

The idea for the solution below came from Stackoverflow.  Working from "bottom to top", *data* is reversed in function problem18.

 (defparameter *data*
                   '((75)
                    (95 64)
                    (17 47 82)
                    (18 35 87 10)
                    (20 04 82 47 65)
                    (19 01 23 75 03 34)
                    (88 02 77 73 07 63 67)
                    (99 65 04 28 06 16 70 92)
                    (41 41 26 56 83 40 80 70 33)
                    (41 48 72 33 47 32 37 16 94 29)
                    (53 71 44 65 25 43 91 52 97 51 14)
                    (70 11 33 28 77 73 17 78 39 68 17 57)
                    (91 71 52 38 17 14 91 43 58 50 27 29 48)
                    (63 66 04 68 89 53 67 30 73 16 69 87 40 31)
                    (04 62 98 27 23 09 70 98 73 93 38 53 60 04 23)))

(defun bottom-up-max (a b)
  (mapcar #'max
          (mapcar #'+ a b)
          (mapcar #'+ (rest a) b)))

(defun problem18 (lst)
  (first (reduce #'bottom-up-max (reverse lst))))

To get the solution, evaluate:
 
(problem18 *data*)