(defun parse-input (input)
  (uiop:read-file-string input))

(defun part-one (input)
  (loop :for (a b c d) :on (coerce (parse-input input) 'list)
	:for i :from 4
	:if (and (not (member a (list b c d)))
		 (not (member b (list a c d)))
		 (not (member c (list a b d)))
		 (not (member d (list a b c))))
	  :return i))