#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <unordered_map>
using namespace std;
#define minv -10000
#define maxv 10001

int main() {
    int q,n;
    int pts[10][2];
    int x_mx ,y_mx;
    int x_mn ,y_mn;
    cin >> q;
    bool flg;
    while(q--){
        cin >> n;
        flg = true;
        x_mx = minv;
        y_mx = minv;
        x_mn = maxv;
        y_mn = maxv;
        for(int i = 0; i < n; i++){
            cin >> pts[i][0] >> pts[i][1] ;
            x_mx = max(pts[i][0],x_mx);
            x_mn = min(pts[i][0],x_mn);
            y_mx = max(pts[i][1],y_mx);
            y_mn = min(pts[i][1],y_mn);
        }
        for(int i= 0; i < n; i++){
            if((pts[i][0] >= x_mn && pts[i][0] <= x_mx && (pts[i][1] == y_mn || pts[i][1] == y_mx)) 
                ||((pts[i][0] == x_mn || pts[i][0] == x_mx) && pts[i][1] >= y_mn && pts[i][1] <= y_mx));
            else{
                cout << "NO" << endl;
                flg = false;
                break;
            }
                
        }
        if(flg==true)
            cout << "YES" << endl;
    }
    return 0;
}