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

int main() {
    int q;
    cin >> q;
    while(q--){
        int n;
        cin >> n;
        int xmax=-10000,xmin=10000,ymax=-10000,ymin=10000;
        vector <pair<int,int>> pts;
        for(int i=0;i<n;i++){
            int x=0,y=0;
            cin >> x >> y;
            if(xmax < x)
                xmax = x;
            if(xmin > x)
                xmin = x;
            if(ymax < y)
                ymax = y;
            if(ymin > y)
                ymin = y;
            
            pts.push_back(make_pair(x,y));
        
        }
//        if(xmax-xmin <= 0 || ymax-ymin <= 0){
//            cout << "NO" << endl;
//            continue;
//        }
        
        int cnt = 0;
        //cout << xmax << xmin << ymax << ymin <<endl;
        for(int i=0;i<pts.size();i++){
            if(pts[i].first == xmin || pts[i].first == xmax || pts[i].second == ymin || pts[i].second == ymax){
                cnt++;
                continue;
            }
            else{
                cout << "NO" << endl;
                break;
            }
        }
        if(cnt == n)
            cout << "YES" << endl;
    }
    return 0;
}