#include <iostream>
#include <algorithm>
using namespace std;
#define rep(i,n) for(int i=0;i<n;i++)
int n, K, x[55], y[55];
long long ans = 1e18 * 4;
int main() {
	cin >> n >> K;
	rep(i, n)cin >> x[i] >> y[i];
	rep(i, n) {
		rep(j, n) {
			rep(k, n) {
				rep(l, n) {
					int cnt = 0;
					rep(m, n)if (min(x[i], x[j]) <= x[m] && max(x[i], x[j]) >= x[m] && min(y[k], y[l]) <= y[m] && max(y[k], y[l]) >= y[m])cnt++;
					if (cnt >= K)ans = min(ans, (long long)abs(x[i] - x[j])*abs(y[k] - y[l]));
				}
			}
		}
	}
	cout << ans << endl;
	getchar();getchar();
}