#include <bits/stdc++.h>
//#include <atcoder/modint>

using namespace std;
//using namespace atcoder;
using ld = long double;
//using mint = modint998244353;

int main(){
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);

    /*
       dp(S, i, j) = 訪れた店の集合がSで現在iにいてj枚ピザをもっている状態での最小値
    */
    int N, K, M;
    ld d;
    cin >> N >> K;
    vector<ld> x(N+1), y(N+1);
    for (int i=0; i<N; i++) cin >> x[i] >> y[i];

    auto dist=[&](int i, int j)->ld{
        return sqrt((x[i]-x[j])*(x[i]-x[j])+(y[i]-y[j])*(y[i]-y[j]));
    };

    M = 1<<N;

    vector dp(M, vector(N+1, vector<ld>(K+1, 1e18)));
    dp[0][N][K] = 0;
    for (int i=0; i<M; i++){
        for (int j=0; j<=N; j++){
            for (int k=0; k<=K; k++){
                if (dp[i][j][k] == 1e18) continue;
                //ピザ屋
                dp[i][N][K] = min(dp[i][N][K], dp[i][j][k]+dist(j, N));
                //家
                for (int l=0; l<N; l++){
                    if (i>>l & 1) continue;
                    if (k>=1) dp[i|(1<<l)][l][k-1] = min(dp[i|(1<<l)][l][k-1], dp[i][j][k] + dist(j, l));

                }
            }
        }
    }
    ld ans=1e18;
    for (int i=0; i<=K; i++) ans = min(ans, dp[M-1][N][i]);
    cout << setprecision(18) << ans << endl;

    return 0;
}