#include <iostream>
#include <vector>
#include <limits>
#include <cmath>

using namespace std;


int main() {
	int N, K;
	cin >> N >> K;

	vector<long long> x(N), y(N);

	for (int i = 0; i < N; i++)
		cin >> x[i] >> y[i];

	long long ans = numeric_limits<long long>::max();

	for (int left = 0; left < N; left++) {
		for (int right = 0; right < N; right++) {
			for (int top = 0; top < N; top++) {
				for (int bottom = 0; bottom < N; bottom++) {

					int cnt = 0;
					for (int i = 0; i < N; i++) {
						if (x[left] <= x[i] && x[i] <= x[right]
							&& y[i] <= y[top] && y[bottom] <= y[i])
							cnt++;
					}
					if (cnt >= K) ans = min(ans, (x[right] - x[left])*(y[top] - y[bottom]));
				}
			}
		}
	}

	cout << ans << endl;

	return 0;
}