#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;
using pii = pair<int,int>;
#define INF 10000000
#define NMAX 10

pii v[NMAX];

int main() {
    int i, q, n, xmin, xmax, ymin, ymax;
    bool ok;
    
    for(cin >> q; q; --q)
    {
        xmin = ymin = INF;
        xmax = ymax = -INF;
        
        cin >> n;
        for(i = 0; i < n; ++i)
        {
            cin >> v[i].first >> v[i].second;
            if(v[i].first < xmin) xmin = v[i].first;
            if(v[i].first > xmax) xmax = v[i].first;
            if(v[i].second < ymin) ymin = v[i].second;
            if(v[i].second > ymax) ymax = v[i].second;
        }
        
        for(ok = true, i = 0; i < n; ++i)
        {
            if(v[i].first != xmin && v[i].first != xmax && v[i].second != ymin && v[i].second != ymax) ok = false;
        }
        
        cout << (ok ? "YES\n" : "NO\n");
    }
    return 0;
}