import           Control.Applicative
import           Control.Arrow
import           Control.Monad
import           Data.Bits
import qualified Data.ByteString.Char8         as B
import           Data.Char
import           Data.List
import qualified Data.Vector.Unboxed           as V
import           Data.Maybe

main = do
  let readInt = fmap (second B.tail) . B.readInt
  a <- fst . fromJust . readInt <$> B.getLine
  putStrLn $ if a >= 30 then "Yes" else "No"
