import Control.Monad
import Data.List

main = do
  n <- readLn
  ws <- replicateM n $ map read . words <$> getLine :: IO [[Int]]
  
  let ws' = map length $ group $ sort $ foldr1 (++) ws
  let s2 = sum $ map (`div` 2) ws'
  let s4 = (`div` 4) $ sum $ map (`mod` 2) ws'
  
  print $ s2 + s4