import Control.Monad
import Data.Maybe
import qualified Data.ByteString.Char8 as BS
import Data.List

readInt = fst . fromJust . BS.readInt
readIntList = map readInt . BS.words
getInt = readInt <$> BS.getLine
getIntList = readIntList <$> BS.getLine

main = do
    [a, b, c, d] <- getIntList
    putStrLn $ takahashi a b c d

takahashi a b c d | a <= 0 = "No"
                  | otherwise = aoki a b (c-b) d
aoki a b c d | c <= 0 = "Yes"
             | otherwise = takahashi (a-d) b c d