#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using ull = unsigned long long;
template <class T>
using max_heap = priority_queue<T>;
template <class T>
using min_heap = priority_queue<T, vector<T>, greater<T>>;
#define rep(i, l, r) for (ll i = (l); i < (r); i++)
#define rrep(i, r, l) for (ll i = (r); i-- > (l);)
#define all(x) begin(x), end(x)
template <class T>
bool chmin(T& lhs, T rhs) {
    return lhs > rhs ? (lhs = rhs, true) : false;
}
template <class T>
bool chmax(T& lhs, T rhs) {
    return lhs < rhs ? (lhs = rhs, true) : false;
}
struct IOIO {
    IOIO() {
        cin.tie(0)->sync_with_stdio(0);
    }
} ioio;
template <class S, class T>
ostream& operator<<(ostream& os, const pair<S, T>& p) {
    os << '(' << p.first << ", " << p.second << ')';
    return os;
}
template <class T>
ostream& operator<<(ostream& os, const vector<T>& vs) {
    os << '{';
    rep(i, 0, (int)vs.size()) os << vs[i] << (i + 1 == (int)vs.size() ? "" : ", ");
    os << '}';
    return os;
}
template <class T>
ostream& operator<<(ostream& os, const set<T>& vs) {
    os << '{';
    for (auto it = vs.begin(); it != vs.end(); it++) {
        if (it != vs.begin()) {
            os << ", ";
        }
        os << *it;
    }
    os << '}';
    return os;
}
template <class T, class U>
ostream& operator<<(ostream& os, const map<T, U>& vs) {
    os << '{';
    for (auto it = vs.begin(); it != vs.end(); it++) {
        if (it != vs.begin()) {
            os << ", ";
        }
        os << *it;
    }
    os << '}';
    return os;
}
#ifdef DEBUG
void dump_func() {
    cerr << endl;
}
template <class Head, class... Tail>
void dump_func(Head&& head, Tail&&... tail) {
    cerr << head;
    if (sizeof...(Tail) > 0) {
        cerr << ", ";
    }
    dump_func(std::move(tail)...);
}
#define dump(...) cerr << "[" + string(#__VA_ARGS__) + "] ", dump_func(__VA_ARGS__)
#else
#define dump(...) static_cast<int>(0)
#endif

void solve() {
    int n, K;
    cin >> n >> K;
    vector<pair<ld, ld>> p(n + 1);
    rep(i, 0, n) {
        ll x, y;
        cin >> x >> y;
        p[i] = {x, y};
    }
    vector dist(n + 1, vector<ld>(n + 1));
    rep(i, 0, n + 1) rep(j, 0, n + 1) {
        dist[i][j] = hypot(p[i].first - p[j].first, p[i].second - p[j].second);
    }
    const ld none = 1e18;
    vector dp(1 << (n + 1), vector(n + 1, vector<ld>(K + 1, none)));
    dp[1 << n][n][K] = 0;
    rep(i, 0, 1 << (n + 1)) rep(j, 0, n + 1) rep(k, 0, K + 1) {
        if (dp[i][j][k] == none) continue;
        rep(l, 0, n + 1) {
            if (l == n) {
                chmin(dp[i][l][K], dp[i][j][k] + dist[j][l]);
            } else if (k > 0 && (i & (1 << l)) == 0) {
                chmin(dp[i | (1 << l)][l][k - 1], dp[i][j][k] + dist[j][l]);
            }
        }
    }
    cout << fixed << setprecision(10);
    cout << dp[(1 << (n + 1)) - 1][n][K] << '\n';
}

int main() {
    int t = 1;

    while (t--) solve();
}