import Control.Applicative ((<$>), (<*>))
import Control.Monad
import Data.List
import Data.ByteString.Char8 (ByteString)
import qualified Data.ByteString.Char8 as B

main :: IO ()
main = do
  B.getLine
  solve <$> B.getLine <*> B.getLine >>= print

solve :: ByteString -> ByteString -> Int
solve ss st = sum $ B.zipWith f ss st
  where
    f c1 c2 = if c1 == c2 then 0 else 1