#include <bits/stdc++.h>
using namespace std;
using namespace chrono;
#if __has_include(<atcoder/all>)
#include <atcoder/all>
using namespace atcoder;
#endif

int main() {
  const auto start = steady_clock::now();

  std::cin.tie(nullptr);
  std::ios_base::sync_with_stdio(false);

  int64_t n;
  cin >> n;
  vector<int64_t> as(n), bs(n);
  for (int64_t i = 0; i < n; i++) {
    cin >> as[i] >> bs[i];
  }

  random_device rnd;
  mt19937 engine(rnd());

  uniform_int_distribution<> randn(0, n - 1);

  int64_t c = 500000000000000000LL;

  auto calc_score = [&] {
    return int64_t(2000000 -
                   100000 * log10(max(abs(as[0] - c), abs(bs[0] - c)) + 1));
  };
  auto f = [&](int64_t a, int64_t b) { return max(abs(a - c), abs(b - c)); };

  pair<int64_t, int64_t> p = {2 * c - as[0], 2 * c - bs[0]};
  auto g = [&](int64_t a, int64_t b) {
    return 2 * logl(abs(a - p.first) + abs(b - p.second)) /
           (logl(2 * abs(a - p.first)) + logl(abs(b - p.second)));
  };

  using T = pair<pair<long double, vector<int64_t>>,
                 pair<vector<int64_t>, vector<int64_t>>>;
  vector<priority_queue<T, vector<T>, greater<>>> pqs(50);
  for (int64_t i = 1; i < n; i++) {
    vector<int64_t> v;
    v.push_back(i);
    pqs[0].push({{g(as[i], bs[i]), v}, {as, bs}});
  }

  long double s = (1LL << 60);
  vector<int64_t> xs;

  while (duration_cast<milliseconds>(steady_clock::now() - start).count() <
         800) {
    for (int64_t i = 0; i < 50; i++) {
      if (pqs[i].empty()) {
        continue;
      }

      auto [pp, qq] = pqs[i].top();
      pqs[i].pop();

      auto [d, v] = pp;
      auto [cs, ds] = qq;

      if (d < s) {
        s = d;
        xs = v;
      }

      if (i + 1 < 50) {
        for (int64_t k = 1; k < n; k++) {
          if (v.back() == k) {
            continue;
          }

          int64_t j = v.back();

          v.push_back(k);

          int64_t w = cs[j], x = ds[j];
          int64_t y = cs[k], z = ds[k];

          cs[j] = cs[k] = (w + x) / 2;
          ds[j] = ds[k] = (y + z) / 2;

          pqs[i + 1].push({{g(cs[k], ds[k]), v}, {cs, ds}});

          cs[j] = w;
          ds[j] = x;
          cs[k] = y;
          ds[k] = z;

          v.pop_back();
        }
      }
    }
  }

  vector<int64_t> us, vs;

  for (int64_t i = 1; i < xs.size(); i++) {
    us.push_back(xs[i - 1] + 1);
    vs.push_back(xs[i] + 1);
  }

  us.push_back(1);
  vs.push_back([&] {
    int64_t ret = 1;
    for (int64_t i = 2; i < n; i++) {
      int64_t x = (as[0] + as[i]) / 2;
      int64_t y = (bs[0] + bs[i]) / 2;

      int64_t a = (as[0] + as[ret]) / 2;
      int64_t b = (bs[0] + bs[ret]) / 2;

      if (f(x, y) < f(a, b)) {
        ret = i;
      }
    }
    ret++;
    return ret;
  }());

  cout << us.size() << '\n';
  for (int64_t i = 0; i < us.size(); i++) {
    cout << us[i] << ' ' << vs[i] << '\n';
  }

  // cerr << calc_score() << endl;
  // for (int64_t i = 0; i < n; i++) {
  //   cerr << as[i] << ' ' << bs[i] << endl;
  // }

  return 0;
}