#include "bits/stdc++.h"

#include <stdio.h>
#include <math.h>

#include "atcoder/all"
#include <float.h>

#include <boost/multiprecision/cpp_int.hpp>
using namespace boost::multiprecision;

using namespace std;
using namespace atcoder;

using ll = long long;
using ull = unsigned long long;
using mint = modint998244353;
using mint2 = modint1000000007;
const double eps = 1e-9;

#define REP(i, n) for (ll i = 0; i < ll(n); ++i)
#define REPI(i, init, n) for (ll i = init; i < ll(n); ++i)
#define REPD(i, init) for (ll i = init; i >=0; --i)
#define REPDI(i, init, n) for (ll i = init; i >=n; --i)
#define REPE(i, c) for (const auto& i : c)
#define TCASE() ll _ttt; cin >> _ttt; while(_ttt--)

using vl = vector<ll>; using vvl = vector<vl>; using vvvl = vector<vvl>; using dl = deque<ll>;
#define VLI(a, n) vector<ll> a; a.assign(n, 0); for(auto& x : a) cin >> x;
#define DLI(a, n) deque<ll> a; a.assign(n, 0); for(auto& x : a) cin >> x;
#define VSI(a, n) vector<string> a; a.assign(n, ""); for(auto& x : a) cin >> x;
#define VVLI(a, n, m, init) vector<vector<ll>> a(n); for(auto& x : a) x.assign(m, init);
using vd = vector<double>; using pl = pair<ll, ll>; using vpl = vector<pl>;

struct uv { ll u; ll v; ll c; };
#define VUVI(a, n) vector<uv> a; a.assign(n, {0, 0, 1}); for(auto& x : a) {cin >> x.u >> x.v; x.u--; x.v--;}
#define VUVCI(a, n) vector<uv> a; a.assign(n, {0, 0, 0}); for(auto& x : a) {cin >> x.u >> x.v >> x.c; x.u--; x.v--;}
vvl to_edge(const ll n, const vector<uv>& v) { vvl ret(n); for (auto& x : v) ret[x.u].push_back(x.v); return ret; }
vvl to_edge_d(const ll n, const vector<uv>& v) { vvl ret(n); for (auto& x : v) { ret[x.u].push_back(x.v); ret[x.v].push_back(x.u); } return ret; }

template <class T = long long> using pql = priority_queue<T>;
template <class T = long long> using pqg = priority_queue<T, vector<T>, greater<T>>;
using vm = vector<mint>; using vvm = vector<vm>;

ostream& operator<<(ostream& os, const mint& v) { os << v.val(); return os; }
void yn(bool f) { std::cout << (f ? "Yes" : "No") << endl; };
template<class T> void ov(const T& v) { for (auto it = v.begin(); it != v.end(); it++) { if (it != v.begin()) cout << " "; cout << *it; } };
template<> void ov(const vm& v) { for (auto it = v.begin(); it != v.end(); it++) { if (it != v.begin()) cout << " "; cout << it->val(); } };

const ll llhuge = 1LL << 60; //十分でかいが多少足しても溢れない数値
auto gmax(const auto& a, const auto& b) { return a > b ? a : b; };
auto gmin(const auto& a, const auto& b) { return a < b ? a : b; };
bool chmin(auto& a, const auto& b) { const auto olda = a; a = gmin(a, b); return olda != a; }
bool chmax(auto& a, const auto& b) { const auto olda = a; a = gmax(a, b); return olda != a; }
void sort(auto& v) { std::ranges::sort(v); };
void rev(auto& v) { std::ranges::reverse(v); };
template<class T> auto p_sum(const T& v) { T ret(v.size()); std::partial_sum(begin(v), end(v), ret.begin()); return ret; };
template<class T, class K = T::key_type, class V = T::mapped_type> [[nodiscard]] V myat(const T& mp, const K& key) { return mp.find(key) == mp.end() ? V() : mp.at(key); }
template<class T> T ceil(const T a, const T b) { return (a + b - 1) / b; }

struct xy {
	double x; double y;
};

double len(xy a, xy b) {
	return sqrt((a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y));
}

int main() {
	cin.tie(nullptr);
	ios::sync_with_stdio(false);

	ll n, K;
	cin >> n >> K;
	vector<xy> v(n);
	REP(i, n) {
		cin >> v[i].x >> v[i].y;
	}

	vector dp(1 << n, vector(n, double(llhuge)));
	vector tlen(1 << n, double(llhuge));
	tlen[0] = 0.0;
	REP(i, n) {
		dp[1 << i][i] = len(v[i], { 0.0 });
	}
	REP(i, 1 << n) {
		bitset<16> bs(i);
		if (bs.count() > K) continue;

		if (bs.count() > 1) {
			REP(j, n) {
				if (!(i & (1 << j))) continue;
				REP(k, n) {
					if (i & (1 << k)) {
						chmin(dp[i][j], dp[i ^ (1 << j)][k] + len(v[j], v[k]));
					}
				}
			}
		}
		if (bs.count() <= K) {
			REP(j, n) {
				if (!(i & (1 << j))) continue;
				chmin(tlen[i], dp[i][j] + len(v[j], { 0.0 }));
			}
		}
	}

	REP(i, 1 << n) {
		for (ll j = i; j > 0; j = (j - 1) & i) {
			chmin(tlen[i], tlen[j] + tlen[i ^ j]);
		}
	}

	cout << fixed << setprecision(10) << tlen[(1 << n) - 1] << endl;
}