#include <iostream>
#include <queue>
#include <map>
#include <list>
#include <vector>
#include <string>
#include <stack>
#include <limits>
#include <climits>
#include <cassert>
#include <fstream>
#include <cstring>
#include <cmath>
#include <bitset>
#include <iomanip>
#include <algorithm>
#include <functional>
#include <cstdio>
#include <ciso646>
#include <set>
#include <array>
#include <unordered_map>
#include <unordered_set>
#include <type_traits>

using namespace std;

#define FOR(i,a,b) for (int i=(a);i<(b);i++)
#define RFOR(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define REP(i,n) for (int i=0;i<(n);i++)
#define RREP(i,n) for (int i=(n)-1;i>=0;i--)

#define inf 0x3f3f3f3f3f3f3f3f
#define PB push_back
#define MP make_pair
#define ALL(a) (a).begin(),(a).end()
#define SET(a,c) memset(a,c,sizeof a)
#define CLR(a) memset(a,0,sizeof a)
#define VS vector<string>
#define VI vector<ll>
#define DEBUG(x) cout<<#x<<": "<<x<<endl
#define MIN(a,b) (a>b?b:a)
#define MAX(a,b) (a>b?a:b)
#define pi 2*acos(0.0)
#define INFILE() freopen("in0.txt","r",stdin)
#define OUTFILE()freopen("out0.txt","w",stdout)
#define ll long long
#define ull unsigned long long
#define pii pair<ll,ll>
#define pcc pair<char,char>
#define pic pair<ll,char>
#define pci pair<char,ll>
#define eps 1e-14
#define FST first
#define SEC second
#define SETUP cin.tie(0), ios::sync_with_stdio(false), cout << setprecision(15) << std::fixed;

namespace {
	struct input_returnner {
		ll N; input_returnner(ll N_ = 0) :N(N_) {}
		template<typename T> operator vector<T>() const { vector<T> res(N); for (auto &a : res) cin >> a; return std::move(res); }
		template<typename T> operator T() const { T res; cin >> res; return res; }
		template<typename T> T operator - (T right) { return T(input_returnner()) - right; }
		template<typename T> T operator + (T right) { return T(input_returnner()) + right; }
		template<typename T> T operator * (T right) { return T(input_returnner()) * right; }
		template<typename T> T operator / (T right) { return T(input_returnner()) / right; }
		template<typename T> T operator << (T right) { return T(input_returnner()) << right; }
		template<typename T> T operator >> (T right) { return T(input_returnner()) >> right; }
	};
	template<typename T> input_returnner in() { return in<T>(); }
	input_returnner in() { return input_returnner(); }
	input_returnner in(ll N) { return std::move(input_returnner(N)); }
}

template < typename T >
struct is_vector : std::false_type {};

template < typename T >
struct is_vector<std::vector<T>> : std::true_type {};

template < typename T >
constexpr bool is_vector_v = is_vector<T>::value;

template <typename T>
std::ostream& operator<< (std::ostream& out, const std::vector<T>& v) {
	if (!v.empty()) {
		for (int i = 0; i < v.size(); ++i) {
			out << v[i] << (i == v.size() - 1 ? "\n" : (is_vector_v<T> ? "" : ", "));
		}
	}
	return out;
}

ll MOD = 1e9 + 7;

class prime {
private:
public:
	std::vector<int> primes;
	std::vector<bool> isPrime;
	prime(int num = 0) {
		if (num == 0) return;
		isPrime.resize(num + 1);
		fill(isPrime.begin(), isPrime.end(), true);
		int ma = sqrt(num) + 1;
		isPrime[0] = isPrime[1] = false;
		int cnt = 0;
		for (int i = 2; i <= ma; ++i) if (isPrime[i]) {
			for (int j = 2; i*j <= num; ++j) {
				isPrime[i*j] = false;
				cnt++;
			}
		}
		primes.reserve(cnt);
		for (int i = 0; i<isPrime.size(); ++i) if (isPrime[i]) {
			primes.push_back(i);
		}
	}

	bool IsPrime(int num) {
		if (num < isPrime.size()) return isPrime[num];
		for (auto p : primes) {
			if (num%p == 0) return false;
		}
		int ma = sqrt(num) + 1;
		for (int i = primes.back(); i <= ma; i += 2) {
			if (num%i == 0) return false;
		}
		return true;
	}

	std::map<int, int> GetFactor(int num) {
		std::map<int, int> res;
		int ma = sqrt(num) + 1;
		int a = 2;
		auto it = primes.begin();
		while (num >= a*a) {
			if (num%a == 0) {
				res[a]++;
				num /= a;
			}
			else {
				if (it == primes.end()) ++a;
				else {
					++it;
					a = *it;
				}
			}
		}
		res[num]++;
		return res;
	}
};

void solve();

signed main() {
	SETUP;
	solve();
#ifdef _DEBUG
	system("pause");
#endif
	return 0;
}

#define int ll

void solve() {
	int N, K; cin >> N >> K;
	set<int> xS, yS;
	vector<pii> ps;
	REP(i, N) {
		int x, y; cin >> x >> y;
		ps.emplace_back(x, y);
		xS.insert(x);
		yS.insert(y);
	}

	unordered_map<int, int> xmap, ymap;
	unordered_map<int, int> xdecode, ydecode;
	{
		int i = 0;
		for (auto &a : xS) {
			xmap[a] = i;
			xdecode[i] = a;
			i++;
		}
		i = 0;
		for (auto &a : yS) {
			ymap[a] = i;
			ydecode[i] = a;
			i++;
		}
	}
	vector<vector<int> > field(ymap.size(),vector<int>(xmap.size()));
	for (auto &p : ps) {
		field[ymap[p.second]][xmap[p.first]] = 1;
	}
	REP(y, field.size()) {
		REP(x, field[y].size()-1) {
			field[y][x + 1] = field[y][x] + field[y][x + 1];
		}
	}
	REP(y, field.size()-1) {
		REP(x, field[y].size()) {
			field[y+1][x] = field[y][x] + field[y+1][x];
		}
	}

	int res = inf;
	REP(ay, field.size()) REP(ax, field[ay].size()){
		FOR(by, ay + 1, field.size()) FOR(bx, ax + 1, field.size()) {
			int cnt = field[by][bx];
			if (ax - 1 >= 0) {
				cnt -= field[by][ax - 1];
			}
			if (ay - 1 >= 0) {
				cnt -= field[ay - 1][bx];
			}
			if (ax - 1 >= 0 and ay - 1 >= 0) {
				cnt += field[ay - 1][ax - 1];
			}
			if (cnt >= K) {
				res = min(res, (ydecode[by] - ydecode[ay])*(xdecode[bx] - xdecode[ax]));
			}
		}
	}
	cout << res << endl;
}


Measured memory_bytes: 256