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

#define CPP_STR(x) CPP_STR_I(x)
#define CPP_CAT(x, y) CPP_CAT_I(x, y)
#define CPP_STR_I(args...) #args
#define CPP_CAT_I(x, y) x##y

#define ASSERT(expr...) assert((expr))

using i8 = int8_t;
using u8 = uint8_t;
using i16 = int16_t;
using u16 = uint16_t;
using i32 = int32_t;
using u32 = uint32_t;
using i64 = int64_t;
using u64 = uint64_t;

using f32 = float;
using f64 = double;
// }}}

constexpr i64 INF = 1'010'000'000'000'000'017LL;

constexpr i64 MOD = 998244353LL;

constexpr f64 EPS = 1e-12;

constexpr f64 PI = 3.14159265358979323846;

#define M5 100007
#define M9 1000000000

#define F first
#define S second

// util {{{
#define FOR(i, start, end) for (i64 i = (start), CPP_CAT(i, xxxx_end) = (end); i < CPP_CAT(i, xxxx_end); ++i)
#define REP(i, n) FOR(i, 0, n)

#define all(x) (x).begin(), (x).end()
#define ll long long int
#define VI vector<ll>
#define VVI vector<VI>

#define ISD true
#define debug(x) \
    if (ISD)     \
    cout << #x << ": " << x << endl

template <typename T, typename U, typename Comp = less<>>
bool chmax(T &xmax, const U &x, Comp comp = {})
{
    if (comp(xmax, x))
    {
        xmax = x;
        return true;
    }
    return false;
}

template <typename T, typename U, typename Comp = less<>>
bool chmin(T &xmin, const U &x, Comp comp = {})
{
    if (comp(x, xmin))
    {
        xmin = x;
        return true;
    }
    return false;
}

int main()
{
    ll N, K;
    cin >> N >> K;
    vector<ll> X(N + 1), Y(N + 1);
    REP(i, N)
    {
        cin >> X[i + 1] >> Y[i + 1];
    }

    auto dis = [&](ll x1, ll y1, ll x2, ll y2)
    {
        return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
    };
    auto calc = [&](int i, int j, bool is0)
    {
        if (is0)
        {
            return dis(0, 0, X[i], Y[i]) + dis(0, 0, X[j], Y[j]);
        }
        else
        {
            return dis(X[i], Y[i], X[j], Y[j]);
        }
    };
    double IN = 100000000000000;
    vector<vector<vector<double>>> dp((1 << N), vector<vector<double>>(K + 1, vector<double>(N + 1, IN)));
    dp[0][K][0] = 0;
    REP(bit, (1 << N))
    {
        REP(k, K + 1)
        {
            REP(i, N + 1)
            {
                if (dp[bit][k][i] == IN)
                {
                    continue;
                }
                if (k > 0)
                {
                    REP(j, N)
                    {
                        chmin(dp[bit | (1 << j)][k - 1][j + 1], dp[bit][k][i] + calc(i, j + 1, 0));
                    }
                }
                REP(j, N)
                {
                    chmin(dp[bit | (1 << j)][K - 1][j + 1], dp[bit][k][i] + calc(i, j + 1, 1));
                }
            }
        }
    }
    double ans = IN;
    REP(k, K + 1)
    {
        REP(i, N + 1)
        {
            chmin(ans, dp[((1 << N) - 1)][k][i] + calc(0, i, 0));
        }
    }
    cout << fixed << setprecision(10) << ans << endl;
}