main::IO()
main = do
  num<-fmap read $ getLine
  wss<-fmap (fmap words) . sequence . replicate num $getLine
  let targetS True xs  = xs 
      targetS False xs = filter (not . (`elem` xs)) ['0'..'9']
      exe ret ([a]:[b]:[c]:[d]:xs) 
        |xs == ["YES"]  = fs False
        |xs == ["NO"]   = fs True
        where fs flag = targetS flag [a,b,c,d] ++ ret
  putStrLn . targetS False . foldl exe [] $wss