#ifndef ONLINE_JUDGE
#define _GLIBCXX_DEBUG
#endif
#include "atcoder/all"
#include <bits/stdc++.h>
#include <climits>
#include <boost/multiprecision/cpp_dec_float.hpp>
#include <boost/multiprecision/cpp_int.hpp>
#include <boost/rational.hpp>
#include <boost/functional/hash.hpp>
// 任意長整数型
using Bint = boost::multiprecision::cpp_int;
// 仮数部が10進数で1024桁の浮動小数点数型(TLEしたら小さくする)
using BReal =
    boost::multiprecision::number<boost::multiprecision::cpp_dec_float<1024>>;
using Rat = boost::rational<Bint>;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
// 型エイリアスの設定
template<typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
using namespace atcoder;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<typename T> inline bool chmin(T &a, T b) { return ((a>b) ? (a = b, true) : (false));}
#define rep(i,s,n) for(int i=s;i<(int)(n);i++)
//decrease rep(s以上, n未満)
#define drep(i,s,n) for(int i=n-1;i>=s;i--)
const long long inf = 1LL<<60;
typedef long long ll;
typedef long double ld;
typedef __int128_t l3;
//pairのsecondでソートsort(p.begin(),p.end(),cmp)
#define cmp [](pair<ll,ll> a, pair<ll,ll> b){return a.second<b.second;}
//cmpArg := 偏角ソート, atan2l(y, x); atan2l(y, x) = [-pi, pi]
#define cmpArg [](const auto &p1, const auto &p2) { return atan2l(p1.second, p1.first) < atan2l(p2.second, p2.first); }
typedef pair<int,int> pi;
typedef pair<long long, long long> P;
typedef pair<ll, pair<ll,ll> > PP;
#define vll vector<ll>
#define vvll vector<vector<ll>>
#define vint vector<int>
#define vvint vector<vector<int>>
#define vmint vector<mint>
#define vvmint vector<vector<mint>>
#define vvch vector<vector<char>>
#define vch vector<char>
#define vvpi vector<vector<pi>>
#define vpi vector<pi>
#define pb push_back
#define eb emplace_back
#define YES cout<<"Yes"<<endl;
#define NO cout<<"No"<<endl;
#define YN { cout << "Yes" << endl; } else { cout << "No" << endl; }
#define all(x) x.begin(), x.end()
#define fi first
#define se second
template<class T>istream& operator>>(istream& i, vector<T> &v) { rep(j___, 0, size(v))i >> v[j___]; return i; }
#define UNIQUE(x) sort(all(x)), x.erase(unique(all(x)), x.end())
int pc(ll x) { return __builtin_popcount(x); } //ビット列にどれだけ1がたっているかを求める pop count
void cincout(){  ios::sync_with_stdio(false);   std::cin.tie(nullptr);  cout<< fixed << setprecision(15);  }
bool out_grid(ll i, ll j, ll h, ll w) { return (!(0<=i && i<h && 0<=j && j<w)); }
#define vc_cout(v){ ll n=v.size(); rep(i___,0,n) cout << v[i___] << " "; cout << endl; }
#define vv_cout(v){ ll n=v.size(); rep(i___,0,n) { rep(j___,0,v[i___].size()){ cout << v[i___][j___] << " ";} cout << endl; }}

using mint = modint998244353;

const int MAX_N = 14;
double dp[1<<MAX_N][MAX_N+1][MAX_N+1];

int main()
{
    int n,k; cin >> n >> k;
    vector<double> x(n), y(n);
    rep(i,0,n) cin >> x[i] >> y[i];
    x.pb(0); y.pb(0); //原点
    auto dist = [&](int i, int j) -> double {
        double dx = x[i] - x[j], dy = y[i] - y[j];
        return sqrt(dx*dx + dy*dy);
    };

    rep(i,0,1<<MAX_N) rep(j,0,MAX_N+1) rep(k,0,MAX_N+1) dp[i][j][k] = inf;
    dp[0][k][n] = 0;
    for(int S=0;S<1<<n;S++) rep(have,0,k+1) rep(last,0,n+1) rep(nxt,0,n+1) {
        if(nxt == n) {
            chmin(dp[S][k][n], dp[S][have][last] + dist(last, nxt));
        } else if(have-1>=0) {
            chmin(dp[S|(1<<nxt)][have-1][nxt], dp[S][have][last] + dist(last, nxt));
        }
    }

    double ans = inf;
    rep(last,0,n+1) rep(have,0,k+1) chmin(ans, dp[(1<<n)-1][have][last] + dist(last, n));
    cout << setprecision(20) << ans << endl;
}