{-# LANGUAGE BangPatterns #-}

import           Control.Monad
import           Control.Monad.Fix
import           Control.Monad.State
import           Data.Char
import           Data.Coerce
import           Data.IORef
import qualified Data.ByteString.Char8             as BSC8
import qualified Data.Vector.Fusion.Stream.Monadic as VFSM
import qualified Data.Vector.Unboxed               as VU
import qualified Data.Vector.Unboxed.Mutable       as VUM

main :: IO ()
main = do
  t  <- readLn :: IO Int
  m  <- readLn :: IO Int
  cs <- seqInput m
  vs <- seqInput m
  dp <- VUM.unsafeNew 20000
  rep m $ \i -> do
    flip fix (vs VU.! i) $ \loop k -> do
      when (vs VU.! i > 0) $ do
        rev t $ \j -> do
          dpj <- VUM.unsafeRead dp j
          dpjpci <- VUM.unsafeRead dp (j + cs VU.! i)
          VUM.unsafeWrite dp (j + cs VU.! i) (max dpjpci (dpj + vs VU.! i))
        loop (k `div` 2)
  ans <- newIORef (0 :: Int)
  rep (t + 1) $ \i -> do
    dpi <- VUM.unsafeRead dp i
    modifyIORef' ans (max dpi)
  print =<< readIORef ans

stream :: Monad m => Int -> Int -> VFSM.Stream m Int
stream !l !r = VFSM.Stream step l
  where
    step x
      | x < r     = return $ VFSM.Yield x (x + 1)
      | otherwise = return $ VFSM.Done
    {-# INLINE [0] step #-}
{-# INLINE [1] stream #-}

rep :: Monad m => Int -> (Int -> m ()) -> m ()
rep n = flip VFSM.mapM_ (stream 0 n)
{-# INLINE rep #-}

streamR :: Monad m => Int -> Int -> VFSM.Stream m Int
streamR !l !r = VFSM.Stream step (r - 1)
  where
    step x
      | x >= l    = return $ VFSM.Yield x (x - 1)
      | otherwise = return $ VFSM.Done
    {-# INLINE [0] step #-}
{-# INLINE [1] streamR #-}

rev :: Monad m => Int -> (Int -> m ()) -> m ()
rev n = flip VFSM.mapM_ (streamR 0 n)
{-# INLINE rev #-}

type CParser a = StateT BSC8.ByteString Maybe a
runCParser :: CParser a -> BSC8.ByteString -> Maybe (a, BSC8.ByteString)
runCParser = runStateT
{-# INLINE runCParser #-}
int :: CParser Int
int = coerce $ BSC8.readInt . BSC8.dropWhile isSpace
{-# INLINE int #-}
seqInput :: Int -> IO (VU.Vector Int)
seqInput n = VU.unfoldrN n (runCParser int) <$> BSC8.getLine
{-# INLINE seqInput #-}