import java.io._
import java.util.StringTokenizer
import scala.util.control.Breaks.{breakable,break}

object Main extends App {
  val in = new InputReader(System.in)
  val pw = new PrintWriter(System.out)

  type IP = (Int, Int)

  def check(p: IP, ps: IP, pl: IP): Boolean = {
    val (nx, ny) = p
    ps._1 <= nx && nx <= pl._1 && ps._2 <= ny && ny <= pl._2
  }


  val N, K = in.next().toInt
  val pos = new Array[IP](N)
  var xs = new Array[Int](N)
  var ys = new Array[Int](N)

  for(i <- 0 until N) {
    val x, y = in.next().toInt
    pos(i) = (x, y)
    xs(i) = x
    ys(i) = y
  }

  xs = xs.sorted
  ys = ys.sorted

  var ans: Long = Long.MaxValue

  for(ix <- 0 until N; jx <- 0 until N; iy <- 0 until N; jy <- 0 until N) {
    val hoge =
      pos
        .filter(check(_, (xs(ix), ys(iy)), (xs(jx), ys(jy))))
        .length
    if(hoge >= K)
      ans = Math.min(ans, (xs(jx).toLong-xs(ix))*(ys(jy)-ys(iy)))
  }
  println(ans)
}


class InputReader(stream: InputStream) {
  private val reader = new BufferedReader(new InputStreamReader(stream))
  private var tokenizer: StringTokenizer = new StringTokenizer(reader.readLine())
  def next(): String = {
    while (!tokenizer.hasMoreTokens()) {
      tokenizer = new StringTokenizer(reader.readLine())
    }
    tokenizer.nextToken()
  }
}

