module Main where

abcd :: String -> (Float, Float, Float, Float)
abcd str =  ( read (head strs)
			, read (head (tail strs))
			, read (head (tail (tail strs)))
			, read (head (tail (tail (tail (strs))))))
	where strs = words str

ans a b c d
	| rsTakahashi < rsAoki = "No"
	| otherwise = "Yes"
	where (rsTakahashi, rsAoki) = (ceiling (a / d) , ceiling (c / b))


main :: IO ()
main = do
	input <- getLine
	let (a, b, c, d) = abcd input
	putStrLn $ ans a b c d
