(defn abc123-A
  "return whether all antennas could talk to each other"
  [xs k]
  (let [min (reduce #(Math/min %1 %2) xs)
        max (reduce #(Math/max %1 %2) xs)]
    (<= (- max min) k)))
(defn main-abc123-A []
  (let [xs (doall (for [_ (range 5)] (read)))
        k (read)]
    (if (abc123-A xs k)
     (println "Yay!")
     (println ":("))))
(main-abc123-A)
