Hacker Rank: Making Anagrams

anagrams.clj

;; https://www.hackerrank.com/challenges/ctci-making-anagrams

(defn char-frequencies
  [x]
  (reduce #(update %1 %2 (fnil inc 0)) {} x))
  
(let [a (read-line)
      b (read-line)
      a-freq (char-frequencies a)
      b-freq (char-frequencies b)
      diff (merge-with - a-freq b-freq)]
  (println (reduce + (map Math/abs (vals diff)))))