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


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */ 
    int n;
    cin >> n;
    for (int i=0; i<n; i++){
        int m;
        cin >> m;
        int xu,xl,yu,yl;
        
        vector<int> ys;
        vector<int> xs;
        
        int x1,y1;
        cin >> x1 >> y1;
        xu=xl=x1;
        yu=yl=y1;
        ys.push_back(y1);
        xs.push_back(x1);
        for (int j=1; j<m;j++){
            int x,y;
            cin >> x >> y;
            if (x<xl)xl=x;
            if (x>xu)xu=x;
            if (y<yl)yl=y;
            if (y>yu)yu=y;
            
       		ys.push_back(y);
        	xs.push_back(x);
        }
        bool bad=false;
        if (xl==xu || yl==yu){
            bad=true;
        }
        else {       
	        for (int j=0; j<m; j++){
	            if ((xs[j] != xl && xs[j] != xu) && (ys[j] != yl && ys[j] != yu))
	                bad=true;        
        	}
        }
            
        if (bad){
            cout << "NO" << endl;
        } else {
            cout << "YES" << endl;
        }
        
    }
    
    return 0;
}