{-# LANGUAGE BangPatterns #-}
import Control.Arrow
import Control.Monad.Fix
import Data.Foldable
import qualified Data.Vector.Unboxed as VU
import qualified Data.Vector.Unboxed.Mutable as VUM
import qualified Data.ByteString.Char8 as B
import Data.ByteString.Internal (accursedUnutterablePerformIO)
import qualified Data.Set as S
import System.IO.Unsafe
import Debug.Trace

unew :: VU.Unbox a => Int -> VUM.IOVector a
unew !n = accursedUnutterablePerformIO $ VUM.unsafeNew n

uread :: VU.Unbox a => Int -> VUM.IOVector a -> a
uread !i !v = accursedUnutterablePerformIO $ VUM.unsafeRead v i

uwrite :: VU.Unbox a => Int -> a -> VUM.IOVector a -> VUM.IOVector a
uwrite !i !a !v =
  accursedUnutterablePerformIO $ VUM.unsafeWrite v i a >> return v

umodify :: VU.Unbox a => Int -> (a -> a) -> VUM.IOVector a -> VUM.IOVector a
umodify !i !f !v =
  accursedUnutterablePerformIO $ VUM.unsafeModify v f i >> return v

uthaw :: VU.Unbox a => VU.Vector a -> VUM.IOVector a
uthaw !v = accursedUnutterablePerformIO $ VU.unsafeThaw v

ufreeze :: VU.Unbox a => VUM.IOVector a -> VU.Vector a
ufreeze !v = accursedUnutterablePerformIO $ VU.unsafeFreeze v

solve :: Int -> Int -> VU.Vector Int -> Int
solve n k hs = uread (n - 1) dp
 where
  -- dp[i]: minimal cost of moving from 1st to i-th place
  dp = VU.foldl'
    ( \(!dp) (!i, !v) -> if i == 0
      then uwrite 0 0 dp
      else uwrite
        i
        ( minimum
          [ uread j dp + abs (v - hs VU.! j)
          | j <- [i - k .. i - 1]
          , 0 <= j
          , j < n - 1
          ]
        )
        dp
    )
    (unew n)
    (VU.indexed hs)

main = do
  let readInt = fmap (second B.tail) . B.readInt

  (n, k) <-
    (\vec -> (vec VU.! 0, vec VU.! 1)) . VU.unfoldrN 2 readInt <$> B.getLine
  hs <- VU.unfoldrN n readInt <$> B.getLine
  print $ solve n k hs
