// Improved version of https://beta.atcoder.jp/contests/abc075/submissions/1685909
// using while instead of for
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))
    var xi = 0
    while(xi < N) {
      var xj = xi + 1
      while(xj < N){
        var yi = 0
        while(yi < N){
          var yj = yi + 1
          while(yj < N){
            val lx = x(xi)
            val rx = x(xj)
            val by = y(yi)
            val uy = y(yj)
 
            var cnt = 0
            var i = 0
            while(i < N) {
              if(lx<=x_(i) && x_(i)<=rx && by<=y_(i) && y_(i)<=uy) cnt = cnt + 1
              i += 1
            }
 
            if(cnt >= K){
              ans = ans.min((rx-lx)*(uy-by))
            }
            yj += 1
          }
          yi += 1
        }
        xj += 1
      }
      xi += 1
    }
    assert(ans > 0)
    println(ans)
  }
}