#include <atcoder/all>
#include <bits/stdc++.h>
using ll = long long;
using ull = unsigned long long;
#define rep(i, n) for(int i = 0; i < (int)(n); i++)
#define REP(i, m, n) for(int i = (int)(m); i < (int)(n); i++)
using namespace std;
using namespace atcoder;
using mint = modint998244353;
const int inf = 1000000007;
const ll longinf = 1ll << 60;

struct Timer {
    chrono::system_clock::time_point start, last_updated;

    Timer() {
        start = chrono::system_clock::now();
        last_updated = chrono::system_clock::now();
    }

    void reset() {
        start = chrono::system_clock::now();
    }

    void update() {
        last_updated = chrono::system_clock::now();
    }

    double getTime() {
        auto now = chrono::system_clock::now();
        return chrono::duration<double>(now - start).count();
    }
    double should_finish_search1() {
        return getTime() > 5.8;
    }
    bool should_reset() {
        auto now = chrono::system_clock::now();
        return chrono::duration<double>(now - last_updated).count() > 1.0 ||
               chrono::duration<double>(now - start).count() > 5.8;
    }
};

Timer timer;
struct Xor128 {
    unsigned x, y, z, w;

    Xor128() : x(123456789), y(362436069), z(521288629), w(88675123){};

    inline unsigned xor128() {
        unsigned t;
        t = x ^ (x << 11);
        x = y;
        y = z;
        z = w;
        return w = (w ^ (w >> 19)) ^ (t ^ (t >> 8));
    }

    int nextInt(int x, int y) {
        return xor128() % (y - x) + x;
    }

    double nextDouble(double a, double b) {
        return (double)(xor128() & 0xffff) / 0xffff * (b - a) + a;
    }
};
auto rnd = Xor128();

double calculate_score(ll x) {
    return 2000000 - 100000 * log10(abs(x) + 1);
}

double calculate_current_score(vector<ll> &a, vector<ll> &b, double t) {
    double ret = 0;
    double bumbo = 0;
    rep(i, a.size()) {
        double res = min(calculate_score(a[i]), calculate_score(b[i]));
        double b = 1;
        // if(i > 0) {
        //     double c = (1 - t);
        //     res *= c;
        //     b = c;
        // }
        if(i == 0) {
            ret += res;
            bumbo += b;
        }
    }
    return ret / bumbo;
}

void output(vector<pair<int, int>> &query) {
    cout << query.size() << endl;
    for(auto [l, r] : query) {
        cout << l + 1 << " " << r + 1 << endl;
    }
}

void do_query(vector<ll> &a, vector<ll> &b, int i, int j) {
    ll x = (a[i] + a[j]) / 2;
    ll y = (b[i] + b[j]) / 2;
    a[i] = a[j] = x;
    b[i] = b[j] = y;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int n;
    cin >> n;
    vector<ll> a(n), b(n);
    rep(i, n) {
        cin >> a[i] >> b[i];
        a[i] -= 5e17;
        b[i] -= 5e17;
    }
    vector<pair<int, int>> query;
    vector<ll> a_state = a, b_state = b;
    rep(_, 50) {
        int x = rnd.nextInt(0, n);
        int y = rnd.nextInt(0, n - 1);
        if(y >= x)
            ++y;
        query.emplace_back(x, y);
        do_query(a_state, b_state, x, y);
    }
    double t0 = 1e5;
    double t1 = 100;
    double tl = 0.95;
    double t = 0;
    int itr = 0;
    double time = 0;
    double best_score = 0;
    vector<pair<int, int>> best_query;
    while(1) {
        if(!(itr & 31)) {
            time = timer.getTime() / tl;
            if(time > 1.0)
                break;
            t = pow(t0, 1 - time) * pow(t1, time);
        }
        double cur = calculate_current_score(a_state, b_state, time);
        vector<ll> na = a, nb = b;
        int idx = rnd.nextInt(0, 50);
        int x, y;
        int type = rnd.nextInt(0, 6);
        if(type == 0) {
            x = rnd.nextInt(0, n), y = rnd.nextInt(0, n - 1);
            if(y >= x)
                ++y;
        } else if(type == 1) {
            x = query[idx].first, y = rnd.nextInt(0, n - 1);
            if(y >= x)
                ++y;
        } else if(type == 2) {
            y = query[idx].second, x = rnd.nextInt(0, n - 1);
            if(x >= y)
                ++x;
        } else {
            x = 0, y = rnd.nextInt(1, n);
        }
        rep(j, 50) {
            if(j == idx) {
                do_query(na, nb, x, y);
            } else {
                do_query(na, nb, query[j].first, query[j].second);
            }
        }
        double nxt = calculate_current_score(na, nb, time);
        double prob = exp((nxt - cur) / t);
        if(rnd.nextDouble(0, 1) < prob) {
            query[idx] = {x, y};
            a_state = na;
            b_state = nb;
            double score = min(calculate_score(na[0]), calculate_score(nb[0]));
            if(score > best_score) {
                best_query = query;
                best_score = score;
            }
        }
    }
    output(best_query);
    for(auto [l, r] : best_query) {
        do_query(a, b, l, r);
    }
    rep(i, n) {
        cerr << a[i] << " " << b[i] << endl;
    }
    cerr << 50 * min(calculate_score(a[0]), calculate_score(b[0])) << endl;
    return 0;
}