#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")

#include <algorithm>
#include <atcoder/all>
#include <bitset>
#include <cassert>
#include <cmath>
#include <ctime>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
using namespace std;
using namespace atcoder;
typedef long long ll;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define repr(i, n) for (int i = (int)(n) - 1; i >= 0; i--)
#define repk(i, k, n) for (int i = k; i < (int)(n); i++)
#define all(v) v.begin(), v.end()
#define mod1 1000000007
#define mod2 998244353
#define mod3 100000007
#define vi vector<int>
#define vs vector<string>
#define vc vector<char>
#define vl vector<ll>
#define vb vector<bool>
#define vvi vector<vector<int>>
#define vvc vector<vector<char>>
#define vvl vector<vector<ll>>
#define vvb vector<vector<bool>>
#define vvvi vector<vector<vector<int>>>
#define vvvl vector<vector<vector<ll>>>
#define pii pair<int, int>
#define pil pair<int, ll>
#define pli pair<ll, int>
#define pll pair<ll, ll>
#define vpii vector<pair<int, int>>
#define vpll vector<pair<ll, ll>>
#define vvpii vector<vector<pair<int, int>>>
#define vvpll vector<vector<pair<ll, ll>>>

template <typename T>
void debug(T e) {
    cerr << e << endl;
}

template <typename T>
void debug(vector<T> &v) {
    rep(i, v.size()) { cerr << v[i] << " "; }
    cerr << endl;
}

template <typename T>
void debug(vector<vector<T>> &v) {
    rep(i, v.size()) {
        rep(j, v[i].size()) { cerr << v[i][j] << " "; }
        cerr << endl;
    }
}

template <typename T>
void debug(vector<pair<T, T>> &v) {
    rep(i, v.size()) { cerr << v[i].first << " " << v[i].second << endl; }
}

template <typename T>
void debug(set<T> &st) {
    for (auto itr = st.begin(); itr != st.end(); itr++) {
        cerr << *itr << " ";
    }
    cerr << endl;
}

template <typename T>
void debug(multiset<T> &ms) {
    for (auto itr = ms.begin(); itr != ms.end(); itr++) {
        cerr << *itr << " ";
    }
    cerr << endl;
}

template <typename T>
void debug(map<T, T> &mp) {
    for (auto itr = mp.begin(); itr != mp.end(); itr++) {
        cerr << itr->first << " " << itr->second << endl;
    }
}

void debug_out() { cerr << endl; }

template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
    cerr << H << " ";
    debug_out(T...);
}

double dist(double x1, double y1, double x2, double y2) {
    double ret = sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
    return ret;
}

int main() {
    ll N, K;
    cin >> N >> K;
    vector<double> x(N);
    vector<double> y(N);
    for (ll i = 0; i < N; i++) {
        cin >> x[i] >> y[i];
    }
    double INF = 100000000000234;
    vector<double> subans((1 << N), INF);
    vector<vector<double>> bitdp((1 << N), vector<double>(N, INF));
    for (ll i = 0; i < N; i++) {
        bitdp[1 << i][i] = dist(0, 0, x[i], y[i]);
    }
    for (ll i = 1; i < (1 << N); i++) {
        for (ll j = 0; j < N; j++) {
            for (ll k = 0; k < N; k++) {
                if ((i >> k) & 1) {
                    continue;
                }
                bitdp[i + (1 << k)][k] =
                    min(bitdp[i + (1 << k)][k],
                        bitdp[i][j] + dist(x[j], y[j], x[k], y[k]));
            }
        }
    }
    for (ll i = 0; i < (1 << N); i++) {
        for (ll j = 0; j < N; j++) {
            subans[i] = min(subans[i], bitdp[i][j] + dist(0, 0, x[j], y[j]));
        }
    }
    vector<double> bitdp2(1 << N, INF);
    bitdp2[0] = 0;
    for (ll i = 0; i < (1 << N); i++) {
        ll x = (1 << N) - 1 - i;
        for (ll j = x;; j = (j - 1) & x) {
            if (j == 0) {
                break;
            }
            ll popcnt = 0;
            for (ll k = 0; k < N; k++) {
                if ((j >> k) & 1) {
                    popcnt++;
                }
            }
            if (popcnt <= K) {
                bitdp2[i + j] = min(bitdp2[i + j], bitdp2[i] + subans[j]);
            }
        }
    }
    cout << setprecision(13) << bitdp2[(1 << N) - 1] << endl;
}