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

int main() 
{
    long q;
    cin >> q;
    
    for (int q0=0; q0<q; q0++)
    {
        long n;
        cin >> n;

        vector<long> xmap, ymap;
        
        long    x_min = 10000, y_min = 10000, 
                x_max = -10000, y_max = -10000;
        
        for (int i=0; i<n; i++)
        {
            long x0, y0;
            cin >> x0 >> y0;

            xmap.push_back(x0);
            ymap.push_back(y0);
            
            x_min = min( x_min, x0 );
            y_min = min( y_min, y0 );
            x_max = max( x_max, x0 );
            y_max = max( y_max, y0 );
        }
        
        bool flag = true;
        
        for (int i=0; i<n; i++)
        {
            if (xmap[i] != x_min && xmap[i] != x_max && 
                ymap[i] != y_min && ymap[i] != y_max)
            {
                flag = false;
                break;
            }
        }
        
        if (!flag)
            cout << "NO" << endl;
        else
            cout << "YES" << endl;
    }
    
    return 0;
}