import Control.Monad
import qualified Data.Set as S

rInt :: String -> Int
rInt = read

iSet = S.singleton (-1)

solve xs yes no
    | length xs == 0            = head $ S.toList result
    | last (head xs) == "YES"   = solve (tail xs) yes' no
    | otherwise                 = solve (tail xs) yes no'
    where
        result  | yes == iSet   = S.difference (S.fromList [0..9]) no
                | otherwise     = S.difference yes no
        yes'    | yes == iSet   = xs'
                | otherwise     = S.difference yes (S.difference yes xs')
        no'     | no == iSet    = xs'
                | otherwise     = S.union no xs'
        xs' = S.fromList $ map (rInt) $ init $ head xs

main = do
    n <- readLn
    xs <- map words <$> replicateM n getLine
    print $ solve xs iSet iSet