#include <iostream>
#include <cmath>
#include <vector>
#include <algorithm>
using namespace std;
const long long Target = 500000000000000000LL;

void Operation(vector<long long>& A, vector<long long>& B, int idx1, int idx2) {
	long long avg1 = (A[idx1] + A[idx2]) / 2LL;
	long long avg2 = (B[idx1] + B[idx2]) / 2LL;
	A[idx1] = avg1; B[idx1] = avg2;
	A[idx2] = avg1; B[idx2] = avg2;
}

int main() {
	// Step 1. 入力
	vector<long long> A(50, 0);
	vector<long long> B(50, 0);
	long long N; cin >> N;
	for (int i = 0; i < N; i++) cin >> A[i] >> B[i];

	// Step 2. 最初のステップ
	vector<pair<int, int>> Answer;
	long long MinV = (1LL << 60);
	long long MinID = -1;
	for (int i = 1; i < N; i++) {
		long long v1 = (A[0] + A[i]) / 2LL;
		long long v2 = (B[0] + B[i]) / 2LL;
		long long err = min(abs(v1 - Target), abs(v2 - Target));
		if (MinV > err) {
			MinV = err;
			MinID = i;
		}
	}
	Operation(A, B, 0, MinID);
	Answer.push_back(make_pair(0, MinID));

	// Step 3. 貪欲法
	long long RemainA = Target * 2 - A[0];
	long long RemainB = Target * 2 - B[0];
	vector<bool> Used(N, false);
	vector<int> Order; Order.push_back(0);
	while (true) {
		vector<pair<long long, int>> Vec;
		for (int i = 1; i < N; i++) {
			if (Used[i] == true) continue;
			long long v1 = abs(RemainA - A[i]); if (v1 >= RemainA) continue;
			long long v2 = abs(RemainB - B[i]); if (v2 >= RemainB) continue;
			Vec.push_back(make_pair(max(v1, v2), i));
		}
		sort(Vec.begin(), Vec.end()); if (Vec.size() == 0) break;
		int idx = Vec[0].second;
		RemainA = min(6LL * Target, 2LL * RemainA - A[idx]);
		RemainB = min(6LL * Target, 2LL * RemainB - B[idx]);
		Order.push_back(idx);
		Used[idx] = true;
	}
	for (int i = 1; i < N; i++) {
		if (Used[i] == false) Order.push_back(i);
	}

	// Step 4. 答えを出す
	for (int i = N - 2; i >= 0; i--) {
		Answer.push_back(make_pair(Order[i], Order[i + 1]));
		Operation(A, B, Order[i], Order[i + 1]);
	}

	// Step 5. 出力
	cout << Answer.size() << endl;
	for (int i = 0; i < Answer.size(); i++) cout << Answer[i].first + 1 << " " << Answer[i].second + 1 << endl;
	return 0;
}