import Control.Applicative ((<$>))

main :: IO ()
main = do
  [a,b] <- map read . words <$> getLine :: IO [Double]
  print $ floor (50*a + floor' (50.0*a/(0.8+0.2*b)))

floor' :: Double -> Double
floor' x = if x-x' > 0.9 then fromIntegral (ceiling x) else x' 
  where
    x' = fromIntegral $ floor x