import Control.Applicative ((<$>))
import Data.ByteString.Char8 (ByteString)
import qualified Data.ByteString.Char8 as B
import Data.List
import Data.Char (isSpace)

main :: IO ()
main = do
  [x, y] <- getl (readil B.readInt)
  B.getLine
  solve x y <$> getl (readil B.readInt) >>= putStrLn

solve :: Int -> Int -> [Int] -> String
solve x y as
  | all f $ zip as (tail as) = "YES"
  | otherwise = "NO"
  where
    f (ai, aj) = ai * y <= aj * x

getl :: (ByteString -> a) -> IO a
getl f = f <$> B.getLine

readil :: Integral a =>  (ByteString -> Maybe (a, ByteString)) -> ByteString -> [a]
readil f = unfoldr g
  where
    g s = do
      (n, s') <- f s
      return (n, B.dropWhile isSpace s')