import Data.Set
import Data.Array
main = do
  n <- readLn
  a <- fmap read . words <$> getLine
  let g = accumArray (flip (:)) [] (0, n) $ zip a [1..]
      dfs s i = findIndex i s + sum [dfs (insert j s) j | j <- g ! i]
  print $ dfs (singleton 0) 0