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

namespace Problem2
{
    class Program
    {
        static void Main(string[] args)
        {
            var q = rl();

            for (long i = 0; i < q; i++)
            {
                Solve();
            }
        }

        struct  Point
        {
            public long X { get; set; }
            public long Y { get; set; }
        }

        public static void Solve()
        {
            var n = rl();

            List<Point> ps = new List<Point>();
            for (int i = 0; i < n; i++)
            {
                var pLine = rla();
                ps.Add(new Point
                {
                    X = pLine[0],
                    Y = pLine[1]
                });
            }

            var yMin = ps.Select(x => x.Y).Min();
            var yMax = ps.Select(x => x.Y).Max();

            var xMin = ps.Select(x => x.X).Min();
            var xMax = ps.Select(x => x.X).Max();

            foreach (var p in ps)
            {
                if (p.Y == yMax || p.Y == yMin)
                {
                    if (!(p.X <= xMax && p.X >= xMin))
                    {
                        Console.WriteLine("NO");
                        return;
                    }
                }
                else
                {
                    if ((p.X != xMax) && (p.X!= xMin))
                    {
                        Console.WriteLine("NO");
                        return;
                    }
                }
            }
            Console.WriteLine("YES");
          
        }

        #region Helper
        public static long rl()
        {
            return long.Parse(Console.ReadLine());
        }

        public static long[] rla()
        {
            var line = Console.ReadLine().Split(' ');
            return Array.ConvertAll(line, long.Parse);
        }

        public static string[] rls()
        {
            return Console.ReadLine().Split(' ');
        }

        public static List<short> GetBitList(long x)
        {
            //4 ~ 0 0 1
            List<short> bitList = new List<short>();
            while (x > 0)
            {
                bitList.Add((short)(x & 1));
                x = x >> 1;
            }
            return bitList;
        }
        #endregion Helper
    }
}