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

  where
    takahasi a b c d | a <= 0 = "No"
    takahasi a b c d | c <= 0 = "Yes"
    takahasi a b c d = aoki a b (c - b) d

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