// #pragma GCC target("avx2")
#pragma GCC optimize("O3")
// #pragma GCC optimize("unroll-loops")
#include<bits/stdc++.h>
// #include<sys/time.h>
// #include<atcoder/segtree>


using namespace std;

// using mint = atcoder::modint998244353;

const int M = 998244353;
const long long LM = 1LL << 60;

using P = pair<int, int>;


int main() {
    cin.tie(0);
    ios::sync_with_stdio(0);
    int n;
    cin >> n;
    vector<long long> a(n), b(n);
    for (int i = 0; i < n; ++i) {
        cin >> a[i] >> b[i];
    }
    long long T = 500000000000000000LL;
    vector<P> ans;
    for (int _ = 0; _ < 50; ++_) {
        // vector<long long> d(n);
        // for (int i = 0; i < n; ++i) {
        //     d[i] = a[i] - b[i];
        // }
        vector<int> idx;
        for (int i = 1; i < n; ++i) {
            idx.push_back(i);
        }
        sort(idx.begin(), idx.end(), [&](int i, int j) {
            return max(abs(a[0] + a[i] - T * 2), abs(b[0] + b[i] - T * 2)) < max(abs(a[0] + a[j] - T * 2), abs(b[0] + b[j] - T * 2));
        });
        int p = 0;
        int q = idx.front();
        ans.emplace_back(p, q);
        auto av = (a[p] + a[q]) / 2;
        auto bv = (b[p] + b[q]) / 2;
        a[p] = av;
        a[q] = av;
        b[p] = bv;
        b[q] = bv;
    }
    cout << ans.size() << '\n';
    for (auto& i : ans) {
        cout << i.first + 1 << ' ' << i.second + 1 << '\n';
    }


    return 0;
}