main = do
  str <- getLine
  let [a,b,c,d] = map read (words str) ::[Int]
  putStrLn $ match (a,b) (c,d) 1
  

match :: (Int, Int) -> (Int, Int) -> Int -> String
match (a, b) (c, d) n
  | a <= 0    = "No"
  | c <= 0    = "Yes"
  | otherwise = if odd n == True
                  then match (a, b) (c-b, d) (n+1)
                  else match (a-d, b) (c, d) (n+1)
