import Control.Applicative ((<$>))
import Data.Bool (bool)

main :: IO ()
main = solve <$> map read <$> words <$> getLine >>= putStrLn

solve :: [Int] -> String
solve [h, w, n, k] = bool "NO" "YES" $ (if r == 0 then n else r) == k
  where r = (h + w -1) `mod` n