import Data.List
import Data.Ord

pmap f (x,y) = (f x, f y)

main = do
 [n,_] <- map read . words <$> getLine
 ds <- map read . words <$> getContents
 print (clean n ds)

clean :: Int -> [Int] -> Int
clean n ds = minimum $ do
 let (neg,pos) = pmap (sortBy (comparing abs)) (partition (<0) ds)
 i <- [(n - length pos) .. (length neg)]
 let nx = abs (last (0:(take i neg)))
 let px = abs (last (0:(take (n-i) pos)))
 return $ 2 * (min nx px) + (max nx px)