import Control.Arrow
import Control.Monad
import Data.List
import qualified Data.ByteString.Char8 as B
import Debug.Trace

main :: IO ()
main = readLine >>= main'
    where
        main' [n, k] = readContents n >>= print . solve k

solve :: Int -> [[Int]] -> Int
solve k xys = minimum [(xmax - xmin) * (ymax - ymin) | xmax <- xs, xmin <- xs, ymax <- ys, ymin <- ys, xmin < xmax, ymin < ymax, satisfy xmin xmax ymin ymax vs]
    where
        vs = map (\[x, y] -> (x, y)) xys 
        (xs, ys) = unzip vs

        satisfy xmin xmax ymin ymax = (>= k) . length . filter ff
            where
                ff (x, y) = xmin <= x && x <= xmax && ymin <= y && y <= ymax

readLine :: IO [Int]
readLine = unfoldr (fmap (second (maybe B.empty snd . B.uncons)) . B.readInt) <$> B.getLine

readContents :: Int -> IO [[Int]]
readContents = flip replicateM readLine