import Control.Monad
import Data.List
import Data.Array
import Data.Array.IO

inf :: Int
inf = 10^18

chmin :: IOUArray Int Int -> Int -> Int -> IO ()
chmin a k v = do
  u <- readArray a k
  when (u > v) (writeArray a k v)

main :: IO ()
main = do
  n <- readLn :: IO Int
  a <- listArray (0, n - 1) . sort . map read . words <$> getLine :: IO (Array Int Int)
  dp <- newArray (0, n) inf :: IO (IOUArray Int Int)
  writeArray dp 0 0
  forM_ [0..n-1] $ \i -> do
    v <- readArray dp i
    when (i + 2 <= n) $ chmin dp (i + 2) (v + a!(i+1) - a!i)
    when (i + 3 <= n) $ chmin dp (i + 3) (v + a!(i+2) - a!i)
  readArray dp n >>= print