#include <bits/stdc++.h>
using namespace std;

uint64_t seed = 1234567891234567891;
uint64_t xorshift64() {
	seed ^= seed << 13;
	seed ^= seed >> 7;
	seed ^= seed << 17;
	return seed;
}
int rand_int(int l, int r) {
	return l + xorshift64() % (r - l);
}

int main() {
	// step #1. input
	int N;
	cin >> N;
	vector<long long> A(N), B(N);
	for (int i = 0; i < N; i++) {
		cin >> A[i] >> B[i];
	}
	
	// step #2. brute force
	const int samples = 1000000;
	vector<bool> used(45, false);
	for (int i = 0; i < 32; i++) {
		used[i] = true;
	}
	double bestdiff = 1.0e+99;
	vector<bool> best;
	for (int id = 1; id <= samples; id++) {
		for (int i = 2; i < N; i++) {
			swap(used[i], used[rand_int(1, i + 1)]);
		}
		double sa = 0.0, sb = 0.0;
		for (int i = 0; i < N; i++) {
			if (used[i]) {
				sa += A[i];
				sb += B[i];
			}
		}
		sa /= 32.0;
		sb /= 32.0;
		double diff = max(abs(sa - 5.0e+17), abs(sb - 5.0e+17));
		if (bestdiff > diff) {
			bestdiff = diff;
			best = used;
		}
	}
	
	// step #3. final calculation
	vector<int> v;
	for (int i = 0; i < N; i++) {
		if (best[i]) {
			v.push_back(i);
		}
	}
	
	// step #4. output
	cout << 31 << endl;
	for (int i = 2; i <= 32; i *= 2) {
		for (int j = 0; j < 32; j += i) {
			cout << v[j] + 1 << ' ' << v[j + i / 2] + 1 << endl;
		}
	}
	cerr << "bestdiff = " << bestdiff << endl;
	
	return 0;
}