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


int main() {
    size_t q;
    cin >> q;
    const int shift = 10000;    
    while(q--) {
        size_t n;
        cin >> n;
        vector<int> x_coord(n);
        vector<int> y_coord(n);
        int x_min = 2 * shift;
        int x_max = - 2 * shift;
        int y_min = 2 * shift;
        int y_max = - 2 * shift;
        for (size_t i = 0; i < n; ++i) {
            cin >> x_coord[i] >> y_coord[i];
            x_min = min(x_min, x_coord[i]);
            x_max = max(x_max, x_coord[i]);
            y_min = min(y_min, y_coord[i]);
            y_max = max(y_max, y_coord[i]);
        }
        
        bool rect = true;
        for (size_t i = 0; i < n; ++i) {
            if ((x_coord[i] != x_min) && (x_coord[i] != x_max) && (y_coord[i] != y_min) && (y_coord[i] != y_max)) {
                rect = false;
                break;
            }
        }
        if (rect) {
            cout << "YES" << endl;
        } else {
            cout << "NO" << endl;
        }
    }
    return 0;
}