#include <bits/stdc++.h>
using namespace std;
#define endl '\n'
#define int long long
#define debug(x) cout << #x << " = " << x << '\n'

const int N = 4010;
const int inf = 0x3f3f3f3f3f3f3f3f;
const int mod = 998244353;

int n;
array<int, 3> a[N];

void solve() {
    cin >> n;
    for(int i = 1; i <= 3 * n; i++) {
        cin >> a[i][0] >> a[i][1];
        a[i][2] = i;
    }
    sort(a + 1, a + 1 + 3 * n);
    for(int i = 1; i <= 3 * n; i += 3) {
        cout << a[i][2] << " " << a[i + 1][2] << " " << a[i + 2][2] << endl;
    }
}

signed main() {
    ios::sync_with_stdio(0);
    cin.tie(0), cout.tie(0);
    int t;
    cin >> t;
    while(t--) solve();
}