#include <bits/stdc++.h>
typedef long long ll;
 
using namespace std;

int main(){
	ll N, K;
	cin >> N >> K;
	vector<ll> x(N), y(N);
	for (int i = 0; i < N; i++){
		cin >> x[i] >> y[i];
	}

	set<ll> X;
	set<ll> Y;
	for (int i = 0; i < N; i++){
		X.insert(x[i]);
		Y.insert(y[i]);
	}

	ll res = 1e18*4;
	for (auto l = X.begin(); l != X.end(); l++){
		for (auto r = X.begin(); r != X.end(); r++){
			for (auto b = Y.begin(); b != Y.end(); b++){
				for (auto t = Y.begin(); t != Y.end(); t++){
					ll cnt = 0;
					for (int i = 0; i < N; i++){
						if (x[i] >= *l && x[i] <= *r){
							if (y[i] >= *b && y[i] <= *t){
								cnt++;
							}
						}
					}

					if (cnt >= K){
						ll s = (*r-*l)*(*t-*b);
						res = min(res, s);
					}
				}
			}
		}
	}

	cout << res << endl;
	return 0;
}
