import Data.Set as Set
import Control.Monad

main = do
  n <- read <$> getLine
  xs <- forM [1..n] $ \t -> do
    read <$> getLine
  putStrLn . show $ solve empty xs

solve :: Set Int -> [Int] -> Int
solve set [] = size set
solve set (x:xs) = if x `member` set then solve (delete x set) xs else solve (insert x set) xs
