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

using i64 = long long;
const int N = 14;

int n, k, x[N], y[N];

double dis[1 << N][N], d[1 << N], dp[1 << N];

int t1(int x) {
    return x ? t1(x >> 1) + 1 : -1;
}

int ppc(int x) {
    return x ? ppc(x - (x & -x)) + 1 : 0;
}

double f(int x, int y) {
    return sqrt(x * (i64)x + y * (i64)y);
}

double f(int i) {
    return f(x[i], y[i]);
}

int main() {
    int n, k;
    cin >> n >> k;
    for(int i = 0; i < n; i ++)
        cin >> x[i] >> y[i];

    for(int i = 1; i < (1 << n); i ++) {
        fill(dis[i], dis[i] + n, 1e15);
        if(i == (i & -i))
            dis[i][t1(i)] = 2 * f(t1(i));
        else{
            for(int j = 0; j < n; j ++) {
                if(!((i >> j) & 1)) continue;
                for(int p = i ^ (1 << j), k = 0; k < n; k ++) {
                    if((p >> k) & 1)
                        dis[i][j] = min(dis[i][j], dis[p][k] - f(k) + f(j) + f(x[j] - x[k], y[j] - y[k]));
                }
            }
        }

        d[i] = *min_element(dis[i], dis[i] + n);
        if(ppc(i) > k) d[i] = 1e15;

        dp[i] = d[i];

        for(int j = i; j; j = (j - 1) & i)
            dp[i] = min(dp[i], dp[j] + d[i ^ j]);
    }

    cout << fixed << setprecision(7) << dp[(1 << n) - 1] << "\n";
}