#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;

int const MAXX = 10005;

int n;
pair < int ,int > a[1000];

bool Check()
{
    int XMAX, YMAX, XMIN, YMIN;
    XMAX = YMAX = -MAXX;
    YMIN = XMIN = MAXX;
    for(int i=1; i<=n; i++)
    {
        XMAX = max(XMAX, a[i].first);
        XMIN = min(XMIN, a[i].first);
        YMAX = max(YMAX, a[i].second);
        YMIN = min(YMIN, a[i].second);
    }
    //if(XMAX == XMIN || YMAX == YMIN) return false;
    for(int i=1; i<=n; i++)
    {
        if(a[i].first != XMAX && a[i].first != XMIN && a[i].second != YMAX && a[i].second != YMIN)  return false;
        if(a[i].first == XMAX && (a[i].second > YMAX || a[i].second < YMIN))  return false;
        if(a[i].first == XMIN && (a[i].second > YMAX || a[i].second < YMIN))  return false;
        if(a[i].second == YMAX && (a[i].first > XMAX || a[i].first < XMIN))  return false;
        if(a[i].second == YMIN && (a[i].first > XMAX || a[i].first < XMIN))  return false;
    }
    return true;
}

int main() {
   // freopen("inp.txt", "r", stdin);
    int T;
    cin >> T;
    while(T--){
        cin >> n;
        for(int i=1; i<=n; i++)
            cin >> a[i].first >> a[i].second;
        if(Check()){
            cout << "YES" << endl;
        }else{
            cout << "NO" << endl;
        }
   }
}