import scala.util.control.Breaks
object Main{
  def main(args:Array[String]) = {
    val sc = new java.util.Scanner(System.in)
    val N = sc.nextInt
    val K = sc.nextInt

    val x_ = Array.ofDim[BigInt](N)
    val y_ = Array.ofDim[BigInt](N)
    for(i <- 0 to N-1){
      x_(i) = sc.nextInt
      y_(i) = sc.nextInt
    }

    val x = x_.sorted
    val y = y_.sorted

    var ans : BigInt = (x(N-1)-x(0)) * (y(N-1)-y(0))
    for(xi <- 0 to N-1){
      for(xj <- xi+1 to N-1){
        for(yi <- 0 to N-1){
          for(yj <- yi+1 to N-1){
            val lx = x(xi)
            val rx = x(xj)
            val by = y(yi)
            val uy = y(yj)

            var cnt = 0
            val br = new Breaks
            br.breakable{
              for(i <- 0 to N-1){
                if(lx<=x_(i) && x_(i)<=rx && by<=y_(i) && y_(i)<=uy) cnt = cnt + 1
                if(cnt >= K) br.break
                if(cnt + (N-1-i) < K) br.break
              }
            }

            if(cnt >= K){
              ans = ans.min((rx-lx)*(uy-by))
            }
          }
        }
      }
    }
    println(ans)
  }
}
