
#include <iostream>
#include <algorithm>
#include <queue>
#include <vector>
using namespace std;
typedef long long ll;
typedef struct pair<int,int> P;
typedef struct pair<int,P> P2;

const ll INF=1000000000000000001;
int main() {

	int n,k;
	ll x[50]={};
	ll y[50]={};

	cin>>n>>k;
	ll total=4000000000000000001;
	for(int i=0;i<n;++i)cin>>x[i]>>y[i];
	for(int i=0;i<n;i++){
		for(int j=0;j<n;j++){
			for(int o=0;o<n;o++){
				for(int l=0;l<n;l++){
					int t=0;
					ll x1=max(x[i],x[j]);
					ll x2=min(x[i],x[j]);
					ll y1=max(y[o],y[l]);
					ll y2=min(y[o],y[l]);
					for(int m=0;m<n;m++){
						if(((x[m]<=x1)&&(x[m]>=x2))&&((y[m]<=y1)&&(y[m]>=y2)))t++;
					}
					if(t>=k)total=min(total,(x1-x2)*(y1-y2));
				}
			}
		}
	}
	cout<<total<<endl;
	return 0;
}
