{-# LANGUAGE ScopedTypeVariables, LambdaCase #-}

import qualified Data.List as List
import qualified Data.Set as Set

main :: IO ()
main = do
    [n] :: [Int] <- map read . words <$> getLine
    aue :: [Int] <- map read. words <$> getLine
    ashita :: [Int] <- map read . words <$> getLine
    print $ maximum [ sum (take k aue) + sum (drop (pred k) ashita) | k <- [1..n]] 