#include <iostream>
#include <iomanip>
#include <cassert>
#include <vector>
#include <cmath>
#include <bit>

int main() {
    std::cin.tie(nullptr)->sync_with_stdio(false);
    
    int N, K;
    std::cin >> N >> K;
    std::vector<int> X(N), Y(N);
    for (int i{} ; i < N ; i++) std::cin >> X[i] >> Y[i];
    const long double INF{(long double)1e18};
    std::vector dp(N, std::vector<long double>(1 << N, INF));
    for (int i{} ; i < N ; i++) {
        dp[i][1 << i] = sqrtl(X[i] * X[i] + Y[i] * Y[i]);
    }
    for (int bit{} ; bit < (1 << N) ; bit++) {
        for (int s{} ; s < N ; s++) if (bit & (1 << s)) {
            for (int t{} ; t < N ; t++) if (!(bit & (1 << t))) {
                if (dp[s][bit] > 1e15) continue;
                int dx{X[s] - X[t]}, dy{Y[s] - Y[t]};
                dp[t][bit | (1 << t)] = std::min(dp[t][bit | (1 << t)], dp[s][bit] + sqrtl(dx * dx + dy * dy));
            }
        }
    }
    std::vector<long double> cost(1 << N, INF);
    cost[0] = 0;
    for (int bit{} ; bit < (1 << N) ; bit++) for (int i{} ; i < N ; i++) if (bit & (1 << i)) {
        if (dp[i][bit] > 1e15) continue;
        cost[bit] = std::min(cost[bit], dp[i][bit] + sqrtl(X[i] * X[i] + Y[i] * Y[i]));
    }
    std::vector<long double> ep(1 << N, INF);
    ep[0] = 0;
    int all{(1 << N) - 1};
    for (int bit{} ; bit < (1 << N) ; bit++) {
        assert(ep[bit] < 1e15);
        int can{all ^ bit};
        for (int mask{can} ; mask ; mask = (mask - 1) & can) {
            if ((int)std::popcount((unsigned)mask) <= K) {
                assert((bit & mask) == 0);
                ep[bit | mask] = std::min(ep[bit | mask], ep[bit] + cost[mask]);
            }
        }
    }
    std::cout << std::fixed << std::setprecision(8) << ep[all] << '\n';
}