#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <bits/stdc++.h>
using namespace std;


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */ 
    int t, n, x, y;
    cin >> t;
    while(t--){
        cin >> n;
        
        vector<pair<int, int> > vec;
        int x1 = INT_MAX, x2 = INT_MIN, y1 = INT_MAX, y2 = INT_MIN;
        bool possible = true;
        
        for(int i = 0; i < n; i++){
            cin >> x >> y;
            vec.push_back({x, y});
            
            x1 = min(x1, x);
            x2 = max(x2, x);
            
            y1 = min(y1, y);
            y2 = max(y2, y);
        }
        
        for(int i = 0; i < n; i++){
            if(vec[i].first != x1 && vec[i].first != x2 && vec[i].second != y1 && vec[i].second != y2){
                possible = false;
                break;
            }
        }
        
        if(possible){
            cout << "YES" << endl;
        }
        else{
            cout << "NO" << endl;
        }
    }
    return 0;
}