#include<bits/stdc++.h>
using namespace std;
#define maxn 10050
struct node
{
    int x,y,id;
} point[maxn];
bool cmp(node a,node b)
{
    if(a.x==b.x)return a.y<b.y;
    return a.x<b.x;
}
int t,n;
int main()
{
    scanf("%d",&t);
    while(t--)
    {
        scanf("%d",&n);
        for(int i=1; i<=3*n; i++)
        {
            scanf("%d%d",&point[i].x,&point[i].y);
            point[i].id=i;
        }
        sort(point+1,point+3*n+1,cmp);
        for(int i=1;i<=3*n;i+=3)
        printf("%d %d %d\n",point[i].id,point[i+1].id,point[i+2].id);
    }
    return 0;
}