import Prelude

main :: IO ()
main = do
  [x, y] <- map read . words <$> getLine
  n <- readLn
  as <- map read . words <$> getLine
  putStrLn $ convert $ solve x y n as

convert :: Bool -> String
convert True  = "YES"
convert False = "NO"

solve :: Int -> Int -> Int -> [Int] -> Bool
solve vx vy n as = let dv = vy - vx
                   in  all id $ map (\(a, d) -> dv * a <= d * vx) $ distances as
  where
    distances :: [Int] -> [(Int, Int)]
    distances (a:[])   = [(a, 536870911)]
    distances (a:b:as) = (a, (b - a)) : distances (b:as)