using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ProblemSolver
{
    class Solution
    {
        static char[] splitors = { ' ' };

        /* Input data here */
        static int n;
        static int[] x;
        static int[] y;

        static void Input()
        {
            n = int.Parse(Console.ReadLine());
            x = new int[n];
            y = new int[n];
            for (int i = 0; i < n; i++)
            {
                string[] str = Console.ReadLine().Split(splitors);
                x[i] = int.Parse(str[0]);
                y[i] = int.Parse(str[1]);
            }
        }

        static void Search()
        {
            int minx = int.MaxValue;
            int miny = int.MaxValue;
            int maxx = int.MinValue;
            int maxy = int.MinValue;

            for (int i = 0; i < n; i++)
            {
                minx = Math.Min(minx, x[i]);
                miny = Math.Min(miny, y[i]);
                maxx = Math.Max(maxx, x[i]);
                maxy = Math.Max(maxy, y[i]);
            }

            for (int i = 0; i < n; i++)
                if (x[i] == minx || x[i] == maxx || y[i] == miny || y[i] == maxy)
                {
                    continue;
                }
                else
                {
                    Console.WriteLine("NO");
                    return;
                }

            Console.WriteLine("YES");
        }

        static void Main(string[] args)
        {
            int testcases = int.Parse(Console.ReadLine());
            for (int i = 0; i < testcases; i++)
            {
                Input();
                Search();
            }
        }
    }
}