#include <bits/stdc++.h>
using namespace std;

#define REP(i,n) for(int i=0;i<(int)(n);i++)
#define ALL(x) (x).begin(), (x).end()

typedef int64_t ll;
typedef long double ld;

const ll INF = 4e18;
const ld EPS = 1e-8;

int main(){
  int N, K;
  cin >> N >> K;
  vector<int> x(N), y(N);
  REP(i, N) cin >> x[i] >> y[i];

  ll ret = INF;
  for(int xmin : x) for (int xmax : x) {
    for (int ymin : y) for (int ymax : y) {
      if(xmin > xmax || ymin > ymax) continue;
      int cnt = 0;
      REP(i, N) if (x[i] >= xmin && x[i] <= xmax && y[i] >= ymin && y[i] <= ymax) ++cnt;
      if(cnt >= K) {
        ret = min(ret, (ll)(xmax - xmin) * (ll)(ymax - ymin));
      }
    }
  }

  cout << ret << endl;
  return 0;
}

