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


int main() {
    
    vector <string> solution;
    int q; cin >> q;
    for (int ii = 0; ii < q; ii++){
        int i, n; cin >> n;
        vector <int> xx, yy;
        int xmin = 10001;
        int ymin = 10001;
        int xmax = -10001;
        int ymax = -10001;
        
        for ( i = 0; i < n; i++){
            int x, y; cin >> x >> y;
            xx.push_back(x);
            yy.push_back(y);
            if (x < xmin) xmin = x;
            if (x > xmax) xmax = x;
            if (y < ymin) ymin = y;
            if (y > ymax) ymax = y;            
            }
//        if (xmax == xmin || ymax == ymin) solution.push_back("NO");
//        else{
            for ( i = 0; i < n; i++){
                if (xx[i] != xmax && xx[i] != xmin && yy[i] != ymax && yy[i] != ymin){
                    solution.push_back("NO");
                    break;
                }
            }
            if (i == n) solution.push_back("YES");
//        }
    }
    
    for (int ii = 0; ii < q; ii++) cout << solution[ii] << endl;
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    return 0;
}