#include <iostream>
#include <algorithm>
#include <vector>
#include <utility>
using namespace std;
typedef long long ll;
int INF=1<<29;

int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	ll N,K;
	cin>>N>>K;
	vector<pair<ll,ll>> axis(N);
	vector<ll> x(N),y(N);
	vector<ll> ans;
	for(int i=0;i<N;i++){
		cin>>x[i]>>y[i];
		axis[i].first=x[i];
		axis[i].second=y[i];
	}
	for(int i=0;i<N;i++){ //left
		for(int j=0;j<N;j++){ //right
			for(int k=0;k<N;k++){ //up
				for(int l=0;l<N;l++){ //down
					if(x[i]>=x[j] || y[l]>=y[k]) continue;
					ll c=0;
					for(int m=0;m<N;m++){
						if(x[i]<=axis[m].first && axis[m].first<=x[j] && y[l]<=axis[m].second && axis[m].second<=y[k]) c++;
					}
					if(c>=K) ans.push_back((x[j]-x[i])*(y[k]-y[l]));
				}
			}
		}
	}
	sort(ans.begin(),ans.end());
	cout<<ans[0]<<endl;
	return 0;
}