import qualified Data.Set as S
import Data.List
import Data.Ord

fork f g (x,y,z) = (f x, g y, z)
snd' (_,y,_) = y

main = do
 n <- readLn
 as <- map read . words <$> getLine
 bs <- map read . words <$> getLine
 let q = S.fromList (zip3 as (repeat 0) [0..])
 print (levelup n q bs)

levelup n q = minimum . take n . map (maximum . map snd' . S.elems . foldl hack q . take n) . tails . cycle

hack q b = S.insert (fork (+ (div b 2)) (+1) m) q'
 where (m,q') = S.deleteFindMin q