#include <bits/stdc++.h>
using namespace std;
using ll = long long;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n, k;
    cin >> n >> k;
    vector<pair<int,int>> a(n);
    for(auto &&[x, y] : a) cin >> x >> y;
    vector<double> dp(1 << n, 1ll << 60);
    array<double, 14> tmp;
    tmp.fill(1ll << 60);
    vector<array<double,14>> dp2(1 << n, tmp);
    auto calc = [&](int x1, int y1, int x2, int y2){
        ll dx = x2 - x1, dy = y2 - y1;
        return sqrt(dx * dx + dy * dy);
    };
    array<array<double,15>,15> T;
    for(int i = 0; i < n; i++){
        auto [x1, y1] = a[i];
        T[i][14] = T[14][i] = calc(0, 0, x1, y1);
        for(int j = i + 1; j < n; j++){
            auto [x2, y2] = a[j];
            T[i][j] = T[j][i] = calc(x1, y1, x2, y2);
        }
    }
    for(int i = 0; i < n; i++){
        dp2[1 << i][i] = T[i][14];
    }
    for(int S = 1; S < (1 << n); S++){
        int popcnt = __builtin_popcount(S);
        if(popcnt <= k){
            double mn = 1ll << 60;
            for(int i = 0; i < n; i++){
                if(~S >> i & 1) continue;
                mn = min(mn, dp2[S][i] + T[i][14]);
                if(popcnt < k){
                    for(int j = 0; j < n; j++){
                        if(S >> j & 1) continue;
                        dp2[S | (1 << j)][j] = min(dp2[S | (1 << j)][j], dp2[S][i] + T[i][j]);
                    }
                }
            }
            dp[S] = mn;
        }else{
            for(int T = (S - 1) & S; T > 0; T = (T - 1) & S){
                dp[S] = min(dp[S], dp[T] + dp[S ^ T]);
            }
        }
    }
    cout << fixed << setprecision(15) << dp.back() << '\n';
}