module Main where

import Control.Applicative
import Control.Monad
import Data.List

main :: IO ()
main = do
    n <- readLn :: IO Int
    a1 <- fmap read . words <$> getLine :: IO [Int]
    a2 <- fmap read . words <$> getLine :: IO [Int]
    let s = sum a1 + sum a2
    let ds = do
            i <- [1 .. n]
            let d1 = sum $ drop i a1
            let d2 = sum $ take (i - 1) a2
            return (d1 + d2)
    print $ s - minimum ds