#include<bits/stdc++.h>
using namespace std;
 
struct Point{int x, y;} p[55];
bool lessx(Point &a, Point &b){return a.x < b.x;}

int main(){
  int n, k, v[55], i, j, l, m, cnt;
  long long ans = 4e18;
  scanf("%d%d", &n, &k);
  for(i = 0; i < n; i++){
    scanf("%d%d", &p[i].x, &p[i].y);
    v[i] = p[i].y;
  }
  sort(p, p+n, lessx);
  sort(v, v+n);
  for(i = 0; i <= n-k; i++){
    for(j = i+k-1; j < n; j++){
      for(l = 0; l <= n-k; l++){
        cnt = 0;
        for(m = l; m < n && cnt < k; m++) if(v[i] <= p[m].y && p[m].y <= v[j]) cnt++;
        if(cnt < k) break;
        ans = min(ans, ((long long) v[j] - v[i])*(p[m-1].x - p[l].x));
      }
    }
  }
  printf("%lld\n", ans);
}
