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

struct Point {
    int x = 0;
    int y = 0;
};

int main() {
    int Q; cin >> Q;
    for (int q = 0; q < Q; ++q) {
        int n; cin >> n;
        
        vector<Point> table;
        
        int maxx = numeric_limits<int>::min();
        int maxy = numeric_limits<int>::min();
        int minx = numeric_limits<int>::max();
        int miny = numeric_limits<int>::max();
        for (int i = 0; i < n; ++i) {
            int x; cin >> x;
            maxx = max(x, maxx);
            minx = min(x, minx);
            int y; cin >> y;
            maxy = max(y, maxy);
            miny = min(y, miny);
            Point p; p.x = x; p.y = y;
            table.push_back(p);
        }
        
        bool yes = true;
        for (auto p : table) {
            if (p.x != maxx && p.x != minx && p.y != maxy && p.y != miny) {
                yes = false;
                break;
            }
        }
            
        if (yes)
            cout << "YES" << endl;
        else
            cout << "NO" << endl;
    }
    
    return 0;
}