(let [st (java.io.StreamTokenizer. (java.io.BufferedReader. *in*))
      ni (fn [] (.nextToken st) (int (.nval st)))
      n (ni)
      m (ni)
      d (ac_library.DSU. n)]
  (dotimes [_ m]
    (let [u (ni) v (ni)] (.merge d u v)))
  (println (count (filter #(= (.leader d %) %) (range n)))))