import Control.Monad (replicateM)

main = do
    [n,k] <- fmap read . words <$> getLine
    zs <-  fmap (fmap read . words) <$> replicateM n getLine
    let rs = fmap (\[x,y] -> (x,y)) zs
    let (xs,ys) = unzip rs
    print $ minimum [ s | x1 <- xs, y1 <- ys,
                    x2 <- xs, y2 <- ys,
                    x1<x2 && y1<y2,
                    let s = (x2-x1)*(y2-y1)
                        m = length $ filter (\(a,b) -> x1<=a&&a<=x2&&y1<=b&&b<=y2) rs,
                    m >= k ]