#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;
using ll=long long;
int main(){
	int n,k;
	cin >> n >> k;
	vector<int> x(n),y(n);
	vector<int> xary,yary;
	for(int i=0;i<n;i++){
		cin >> x[i] >> y[i];
		xary.push_back(x[i]);
		yary.push_back(y[i]);
	}
	sort(begin(xary),end(xary));
	sort(begin(yary),end(yary));
	ll ans=1LL*(xary[n-1]-xary[0])*(yary[n-1]-yary[0]);
	for(int xi=0;xi<n;xi++){
		for(int xj=xi+1;xj<n;xj++){
			for(int yi=0;yi<n;yi++){
				for(int yj=yi+1;yj<n;yj++){
					int num=0;
					ll lx=xary[xi],rx=xary[xj];
					ll by=yary[yi],uy=yary[yj];
					for(int i=0;i<n;i++){
						if(lx<=x[i]&&x[i]<=rx&&by<=y[i]&&y[i]<=uy) num++;
					}
					if(num>=k) ans=min(ans,1LL*(rx-lx)*(uy-by));
				}
			}
		}
	}
	cout << ans << endl;
	return 0;
}
