#include <bits/stdc++.h>
#define For(i, a, b) for(int i = a; i < b; i++)
#define rep(i, n) For(i, 0, n)
#define rFor(i, a, b) for(int i = a; i >= b; i--)
#define ALL(v) (v).begin(), (v).end()
#define rALL(v) (v).rbegin(), (v).rend()
using namespace std;

using lint = long long;
using ld = long double;

int INF = 2000000000;
lint LINF = 1000000000000000000;

struct Point {
    ld x, y;
};

ld dist(Point a, Point b) {
    ld dx = a.x - b.x, dy = a.y - b.y;
    return sqrt(dx * dx + dy * dy);
}

int main() {
    int n, K;
    cin >> n >> K;
    n++;
    vector<Point> p(n);
    p[0] = {0.0, 0.0};
    For(i, 1, n) {
        cin >> p[i].x >> p[i].y;
    }
    vector<vector<vector<ld>>> dp(1 << n, vector<vector<ld>>(n, vector<ld>(K + 1, 1000000000000000000)));
    dp[1][0][K] = 0.0;
    rep(s, (1 << n)) {
        rFor(i, n - 1, 0) {
            rep(j, K + 1) {
                if (i == 0 && j != K) {
                    continue;
                }
                rep(ni, n) {
                    if (i == ni) {
                        continue;
                    }
                    if (ni == 0) {
                        ld d = dist(p[i], p[ni]);
                        /*if (dp[s][0][K] > dp[s][i][j] + d) {
                            cout << s << " " << i << " " << j << " -> " << s << " " << 0 << " " << K << endl;
                            dp[s][0][K] = dp[s][i][j] + d;
                            cout << dp[s][0][K] << endl;
                        }*/
                        dp[s][0][K] = min(dp[s][0][K], dp[s][i][j] + d);
                    } else {
                        if (s & (1 << ni) || j == 0) {
                            continue;
                        }
                        int ns = s | (1 << ni);
                        ld d = dist(p[i], p[ni]);
                        /*
                        if (dp[ns][ni][j - 1] > dp[s][i][j] + d) {
                            cout << s << " " << i << " " << j << " -> " << ns << " " << ni << " " << j - 1 << endl;
                            dp[ns][ni][j - 1] = dp[s][i][j] + d;
                            cout << dp[ns][ni][j - 1] << endl;
                        }*/
                        dp[ns][ni][j - 1] = min(dp[ns][ni][j - 1], dp[s][i][j] + d);
                    }
                }
            }
        }
    }
    /*
    rep(s, (1 << n)) rep(i, n) rep(j, K + 1) {
        if (dp[s][i][j] != 2000000000) {
            cout << s << " " << i << " " << j << " " << dp[s][i][j] << endl;
        }
    }
    */
    ld ans = 1000000000000000000;
    rep(j, K + 1) {
        ans = min(ans, dp[(1 << n) - 1][0][j]);
    }
    cout << fixed << setprecision(10) << ans << endl;
}