import Control.Applicative
import Data.List

main = do
    [a,b,c,d] <- map read . words <$> getLine
    putStrLn $ if (solve a b c d) then "Yes" else "No"

solve a b c d = e<=d || (f<=d && g<=d)
    where e = abs (a-c)
          f = abs (a-b)
          g = abs (b-c)