#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;

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];
    vector<pair<int, int>> query;
    for(int i = 1; i <= 16; i *= 2) {
        rep(j, 16 / i) {
            int l = 2 * j * i, r = (2 * j + 1) * i;
            ll x = (a[l] + a[r]) / 2;
            ll y = (b[l] + b[r]) / 2;
            a[l] = a[r] = x;
            b[l] = b[r] = y;
            query.push_back({l, r});
        }
    }
    // cerr << a[0] << " " << b[0] << endl;
    for(auto [l, r] : query) {
        cout << l + 1 << " " << r + 1 << endl;
    }
    double score = 2000000 - 100000 * log10(max(abs(a[0] - (ll)5e17), abs(b[0] - (ll)5e17)) + 1);
    cerr << score * 50 << endl;
    return 0;
}