main = do
  str <- getLine
  let n = read str ::Int
  str <- getLine
  let list1 = take n $ map read (words str) ::[Int]
  str <- getLine
  let list2 = take n $ map read (words str) ::[Int]
  let list = [list1] ++ [list2]
  print $ maximum $ map sum $ cal list n


cal :: [[Int]] -> Int -> [[Int]]
cal list n
  | n < 1     = []
  | otherwise = [take n (list !! 0) ++ drop (n-1) (list !! 1)] ++ (cal list (n-1))
