#include <bits/stdc++.h>

using namespace std;
#define IOS ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr)
#define rep(a, b, c) for(int (a)=(b);(a)<=(c);(a)++)
#define per(a, b, c) for(int (a)=(b);(a)>=(c);(a)--)
#define mset(var, val) memset(var,val,sizeof(var))
#define ll long long
#define int ll
#define fi first
#define se second
#define pb push_back
// #define endl "\n"
#define pii pair<int,int>
#define pll pair<ll,ll>
#define dbg(x...) do{cout<<#x<<" -> ";err(x);}while (0)

void err() { cout << '\n'; }

template<class T, class... Ts>
void err(T arg, Ts... args) {
    cout << arg << ' ';
    err(args...);
}

const int N = 3e3+5;
int n;

struct node {
    int x, y, id;
    bool operator <(const node &B)const{
        return (x > B.x) || (x == B.x && y < B.y);
    }
}a[N];

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

signed main() {
    IOS;
    int T = 1;
    cin >> T;
    while (T--) {
        solve();
    }
    return 0;
}