module Main where
 
main :: IO ()
main = print =<< solve <$> (getLine *> getIntList)
 
solve :: [Int] -> Int
solve a = sum $ go a
  where
  go [] = [0]
  go [x] = [0]
  go (x : xs) = (foldr step 0 $ zip xs [1 ..]) : go xs
    where
    step (y, i) acc = (+acc) . (*2) . (*i) . abs $ x - y
 
getIntList :: IO [Int]
getIntList = map read . words <$> getLine