import qualified AtCoder.Dsu as Dsu
import Control.Monad (forM_)
import qualified Data.ByteString.Char8 as BS
import Data.Maybe (fromJust)

main :: IO ()
main = do
  ints <- map (fst . fromJust . BS.readInt) . BS.words <$> BS.getContents
  let n = head ints
      m = ints !! 1
      pairs (a : b : xs) = (a, b) : pairs xs
      pairs _ = []
  d <- Dsu.new n
  forM_ (take m (pairs (drop 2 ints))) $ \(u, v) -> do
    _ <- Dsu.merge d u v
    pure ()
  leaders <- mapM (Dsu.leader d) [0 .. n - 1]
  print (length (filter id (zipWith (==) leaders [0 ..])))