{-# OPTIONS_GHC -O2 -funbox-strict-fields #-}
import           Control.Monad (replicateM)
import           Data.Int      (Int64)
import           Data.List     (minimum, sort)

type Point = (Int64, Int64)
type Rect = (Int64, Int64, Int64, Int64)

main :: IO ()
main = do
  [n, k] <- readInts
  xys <- replicateM n readPoint
  print $ solve n k xys

solve :: Int -> Int -> [Point] -> Int64
solve n k xys = minimum $ map area rs where
  rs = [(x1, x2, y1, y2) | x1 <- init xs
                         , x2 <- tail xs
                         , y1 <- init ys
                         , y2 <- tail ys
                         , isValid (x1, x2, y1, y2)
                         ]
  (xs, ys) = (sort (map fst xys), sort (map snd xys))
  isValid r = length (filter (isIncluded r) xys) >= k

isIncluded :: Rect -> Point -> Bool
isIncluded (x1, x2, y1, y2) (a, b) = x1 <= a && a <= x2 && y1 <= b && b <= y2

area :: Rect -> Int64
area (x1, x2, y1, y2) = (x2 - x1) * (y2 - y1)

readInts :: Read a => IO [a]
readInts = map read . words <$> getLine

readPoint :: IO Point
readPoint = do
  [x, y] <- readInts
  return (x, y)
