#include <bits/stdc++.h>

using namespace std;


struct edge {
    unsigned short int v, u;
    double e;
    bool operator<(edge b) {
        return e < b.e;
    }
    edge(unsigned short int _v = 0, unsigned short int _u = 0, long double _e = 0) {
        v = _v;
        u = _u;
        e = _e;
    }
};

const int C = 330;

array <unsigned short int, 3> p[50050];
vector <edge> e;

long double dis(array <unsigned short int, 3> a, array <unsigned short int, 3> b) {
    return sqrt((a[0] - b[0]) * (a[0] - b[0]) + (a[1] - b[1]) * (a[1] - b[1]));
}

int dsu[50050];
int ran[50050];

int get(int v) {
    if (dsu[v] == v) {
        return v;
    }
    else {
        return dsu[v] = get(dsu[v]);
    }
}

void unite(int a, int b) {
    a = get(a);
    b = get(b);
    if (ran[a] < ran[b]) {
        dsu[a] = b;
    }
    else {
        dsu[b] = dsu[a];
        if (ran[a] == ran[b]) {
            ran[b]++;
        }
    }
}

bool cmp(array <int, 3> a, array <int, 3> b) {
    return a[1] < b[1] || (a[1] == b[1] && a[0] < b[0]);
}

int32_t main() {
    e.reserve(50000 * C);
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    for (int i = 0; i < 50050; i++) {
        dsu[i] = i;
    }
    int n;
    cin >> n;
    for (int i = 0; i < n; i++) {
        cin >> p[i][0] >> p[i][1];
        p[i][2] = i;
    }
    sort(p, p + n);
    for (int i = 0; i < n; i++) {
        for (int j = i + 1; j < min(n, i + C + 200); j++) {
            double d = dis(p[i], p[j]);
            if (n > 10000 && d > 1000) {
                continue;
            }
            e.push_back({p[i][2], p[j][2], d});
        }
    }
    sort(e.begin(), e.end());
    vector <array <int, 2> > ans;
    long double ansv = 0;
    for (auto ed : e) {
        if (get(ed.v) == get(ed.u)) {
            continue;
        }
        else {
            ansv += ed.e;
            ans.push_back({ed.v, ed.u});
            unite(ed.v, ed.u);
        }
    }
    cout.precision(20);
    cout << fixed;
    cout << ansv << "\n";
    for (auto z : ans) {
        cout << z[0] + 1 << " " << z[1] + 1 << "\n";
    }
    return 0;
}