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


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */  
    long long q;
    long long n;
    cin >> q;
    for(long long i = 0; i < q; i++){
        cin >> n;
        long long x, y;
        //set<int> xs;
        //set<int> ys;
        long long maxx = -100000;
        long long minx = 1e6;
        long long maxy = -100000;
        long long miny = 1e6;
        vector<pair<long long, long long> > points;
        points.clear();
        //xs.clear();
        //ys.clear();
        for(int j = 0; j < n; j++){
            cin >> x >> y;
            //xs.insert(x);
            maxx = max(x, maxx);
            minx = min(x, minx);
            maxy = max(y, maxy);
            miny = min(y, miny);
            //ys.insert(y);
            points.push_back(make_pair(x, y));
        }
        
        //cout << minx << " " << maxx << endl;
        for(int j = 0; j < points.size(); j++){
            if(points[j].first < maxx && points[j].first > minx){
                if(points[j].second != miny && points[j].second != maxy){
                    cout << "NO" << endl;
                    break;
                }
            }
            if(points[j].second < maxy && points[j].second > miny){
                if(points[j].first != minx && points[j].first != maxx){
                    cout << "NO" << endl;
                    break;
                }
            } 
            if(j == points.size() -1){
                cout <<"YES" << endl;
            }
        }
    }
    return 0;
}