#include <bits/stdc++.h>
using namespace std;
const int N = 15;
pair <int, int> a[N];
int n;

int main() {
    int q; cin >> q;
    while (q--) {
        cin >> n;
        for (int i = 0; i < n; i++) cin >> a[i].first >> a[i].second;
        pair <int, int> topleft, botright;
        topleft = botright = a[0];
        for (int i = 1; i < n; i++) {
            topleft.first = min(topleft.first, a[i].first);
            topleft.second = max(topleft.second, a[i].second);
            botright.first = max(botright.first, a[i].first);
            botright.second = min(botright.second, a[i].second);
        }
        bool k = true;
        for (int i = 0; i < n; i++) {
            if (a[i].first > botright.first || a[i].first < topleft.first) {
                cout << "NO" << endl;
                k = false;
                break;
            } 
            if (a[i].second > topleft.second || a[i].second < botright.second) {
                cout << "NO" << endl;
                k = false;
                break;
            }
            if (a[i].first != topleft.first && a[i].first != botright.first && a[i].second != topleft.second && a[i].second != botright.second) {
                cout << "NO" << endl;
                k = false;
                break;
            }
        }
        if (k) cout << "YES" << endl;
    }
}