#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define int ll

const int N = 1e6+10,mo = 1e9+7;

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


inline void solve(){
    int n;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){
        cout<<a[i].id<<" ";
        if(i%3==0){
            cout<<endl;
        }
    }
    cout<<endl;
    

}



signed main(){
    ios::sync_with_stdio(false),cin.tie(0),cout.tie(0);
    int WTN666=1;
    cin>>WTN666;
    while(WTN666--){
        solve();
    }
}