#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <cstring>
#include <cmath>
#include <limits>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <functional>
#include <iomanip>

using namespace std;

#ifdef LOCAL
#define eprintf(...) fprintf(stderr, __VA_ARGS__)
#else
#define eprintf(...) 42
#endif
using ll = long long;
using vll = std::vector<ll>;
using vvll = std::vector<vll>;
using vvvll = std::vector<vvll>;
#define reps(i, S, E) for (ll i = (S); i <= (E); i++)
#define rep(i, N) reps(i, 0, N-1)
#define deps(i, E, S) for (ll i = (E); i >= (S); i--)
#define dep(i, N) deps(i, N-1, 0)
const ll INF = 1LL << 60;
const int INF_INT = 1 << 30;

template<class T> inline bool chmax(T &a, T b) { if (a < b) { a = b; return true; }return false; }
template<class T> inline bool chmin(T &a, T b) { if (a > b) { a = b; return true; }return false; }
struct mll {
	static ll MOD;
	ll val;
	mll(ll v = 0) : val(v % MOD) { if (val < 0) val += MOD; }
	mll operator - () const { return -val; }
	mll operator + (const mll &b) const { return val + b.val; }
	mll operator - (const mll &b) const { return val - b.val; }
	mll operator * (const mll &b) const { return val * b.val; }
	mll operator / (const mll &b) const { return mll(*this) /= b; }
	mll operator + (ll b) const { return *this + mll(b); }
	mll operator - (ll b) const { return *this - mll(b); }
	mll operator * (ll b) const { return *this * mll(b); }
	friend mll operator + (ll a, const mll &b) { return b + a; }
	friend mll operator - (ll a, const mll &b) { return -b + a; }
	friend mll operator * (ll a, const mll &b) { return b * a; }
	mll &operator += (const mll &b) { val = (val + b.val) % MOD; return *this; }
	mll &operator -= (const mll &b) { val = (val + MOD - b.val) % MOD; return *this; }
	mll &operator *= (const mll &b) { val = (val*b.val) % MOD; return *this; }
	mll &operator /= (const mll &b) {
		ll c = b.val, d = MOD, u = 1, v = 0;
		while (d) {
			ll t = c / d;
			c -= t * d; swap(c, d);
			u -= t * v; swap(u, v);
		}
		val = val * u % MOD;
		if (val < 0) val += MOD;
		return *this;
	}
	mll &operator += (ll b) { return *this += mll(b); }
	mll &operator -= (ll b) { return *this -= mll(b); }
	mll &operator *= (ll b) { return *this *= mll(b); }
	mll &operator /= (ll b) { return *this /= mll(b); }
	bool operator == (const mll &b) { return val == b.val; }
	bool operator != (const mll &b) { return val != b.val; }
	bool operator == (ll b) { return *this == mll(b); }
	bool operator != (ll b) { return *this != mll(b); }
	friend bool operator == (ll a, const mll &b) { return mll(a) == b.val; }
	friend bool operator != (ll a, const mll &b) { return mll(a) != b.val; }
	friend ostream &operator << (ostream &os, const mll &a) { return os << a.val; }
	friend istream &operator >> (istream &is, mll &a) { return is >> a.val; }
	static mll Combination(ll a, ll b) {
		chmin(b, a - b);
		if (b < 0) return mll(0);
		mll c = 1;
		rep(i, b) c *= a - i;
		rep(i, b) c /= i + 1;
		return c;
	}
};
using vmll = std::vector<mll>;
using vvmll = std::vector<vmll>;
using vvvmll = std::vector<vvmll>;
using vvvvmll = std::vector<vvvmll>;

struct Fast {
	Fast() {
		cin.tie(0);
		ios::sync_with_stdio(false);
		cout << fixed << setprecision(std::numeric_limits<double>::max_digits10);
	}
} fast; //cin,cout高速化のおまじない＋桁数指定

ll mll::MOD = (ll)(1e9 + 7);// 998244353ll;

//2次元累積和の配列をもとに領域内の和を求める。1basedな配列を入力とする
ll SumFromIntegral(vvll &integral, ll left, ll top, ll right, ll bottom) {
	ll result = 0;

	result += integral[bottom][right];
	result += integral[top - 1][left - 1];
	result -= integral[top - 1][right];
	result -= integral[bottom][left - 1];

	return result;
}

int main() {
	ll N;
	cin >> N;
	ll K;
	cin >> K;
	vector<ll> X(N);
	vector<ll> Y(N);
	rep(i, N) {
		cin >> X[i] >> Y[i];
	}
	
	//それぞれの軸でソートした座標値。indexからここを引いて元の座標値を知ることができる
	vll xSort(N);
	vll ySort(N);
	rep(i, N) {
		xSort[i] = X[i];
		ySort[i] = Y[i];
	}
	std::sort(xSort.begin(), xSort.end());
	std::sort(ySort.begin(), ySort.end());

	map<ll, ll> xIndex;
	map<ll, ll> yIndex;
	rep(i, N) {
		xIndex[xSort[i]] = i;
		yIndex[ySort[i]] = i;
	}

	//座標圧縮してNxNの配列に置き換える。このときindex+1しておき、累積和を扱いやすくする
	vvll integral(N + 1, vll(N + 1, 0));
	rep(i, N) {
		ll u = xIndex[X[i]] + 1;
		ll v = yIndex[Y[i]] + 1;
		integral[v][u] += 1;
	}

	//2次元累積和を求める
	reps(iY, 1, N) reps(iX, 1, N) {
		integral[iY][iX] += integral[iY - 1][iX];
		integral[iY][iX] += integral[iY][iX - 1];
		integral[iY][iX] -= integral[iY - 1][iX - 1];
	}

	//ll SumFromIntegral(vvll &integral, ll left, ll top, ll right, ll bottom);

	ll result = (ll)(1e18 * 5);

	//あり得る矩形を全探索
	reps(left, 1, N - 1) reps(top, 1, N - 1) reps(right, left + 1, N) reps(bottom, top + 1, N) {
		ll numPoint = SumFromIntegral(integral, left, top, right, bottom);
		if (numPoint >= K) {
			ll area = (xSort[right - 1] - xSort[left - 1]) * (ySort[bottom - 1] - ySort[top - 1]);
			chmin(result, area);
		}
	}

	cout << result << endl;

	return 0;
}


Measured memory_bytes: 256