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


int main() {
    ios::sync_with_stdio(false);
    cin.tie(NULL);
    
    int q;
    cin >> q;
    while (q--) {
        int n;
        cin >> n;
        vector <pair<int, int>> pts(n);
        int minX = 1e9, maxX = -1e9;
        int minY = 1e9, maxY = -1e9;
        for (int i = 0; i < n; ++i) {
            cin >> pts[i].first >> pts[i].second;
            minX = min(minX, pts[i].first);
            maxX = max(maxX, pts[i].first);
            minY = min(minY, pts[i].second);
            maxY = max(maxY, pts[i].second);
        }
        
        bool ok = true;
        for (int i = 0; i < n; ++i) {
            if (pts[i].first != minX and pts[i].first != maxX and pts[i].second != minY and pts[i].second != maxY) {
                ok = false;
                break;
            }
        }
        cout << (ok ? "YES\n" : "NO\n");
    }
    return 0;
}