#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = unsigned long long;
#define MOD 1000000007

int main(){
  int n,k;
  cin>>n>>k;
  ll x[n], y[n], x2[n], y2[n];
  for(int i=0;i<n;i++){
    cin>>x[i]>>y[i];
    x2[i]=x[i], y2[i]=y[i];
  }
  sort(x2, x2+n);
  sort(y2, y2+n);
  ll ans=LLONG_MAX;
  for(int xi=0;xi<n;xi++){
    for(int xi2=xi+1;xi2<n;xi2++){
      for(int yi=0;yi<n;yi++){
        for(int yi2=yi+1;yi2<n;yi2++){
          int sum=0;
          for(int i=0;i<n;i++){
            if( x[i]>=x2[xi]&&x[i]<=x2[xi2] && y[i]>=y2[yi]&&y[i]<=y2[yi2] ) sum++;
          }
          if(sum>=k){
            ans=min(ans, (x2[xi2]-x2[xi])*(y2[yi2]-y2[yi]) );
          }
        }
      }
    }
  }
  cout<<ans<<endl;
  return 0;
}