main = do
    _ <- getLine
    sushi <- getLine
    let sushiList = map read (words sushi) :: [Int]
    let dpt = dp sushiList
    putStrLn $ show $ head dpt

dp :: [Int] -> [Int]
dp dt = foldl (\(d1:d2:dx) x -> (max d1 (d2 + x)):d1:d2:dx) [0,0] dt