import Data.List
import qualified Data.Set as S

main =
  putStrLn . head . S.elems . foldl f (S.fromList $ map show [0..9]) . map (splitAt 4 . words) . drop 1 . lines =<< getContents
  where
    f s (l,["YES"]) = S.intersection s $ S.fromList l
    f s (l,["NO"])  = S.difference   s $ S.fromList l