using System;
using System.Globalization;
using System.IO;
using System.Linq;

namespace CF317
{
    internal class Program
    {
        private static void Main(string[] args)
        {
            var sr = new InputReader(Console.In);
            //var sr = new InputReader(new StreamReader("input.txt"));
            var task = new Task();
            using (var sw = Console.Out)
            //using (var sw = new StreamWriter("output.txt"))
            {
                task.Solve(sr, sw);
                //Console.ReadKey();
            }
        }
    }

    internal class Task
    {
        public void Solve(InputReader sr, TextWriter sw)
        {
            var q = sr.NextInt32();
            for (var t = 0; t < q; t++)
            {
                var n = sr.NextInt32();
                var points = new Tuple<int, int>[n];
                for (var i = 0; i < n; i++)
                {
                    var input = sr.ReadArray(Int32.Parse);
                    points[i] = new Tuple<int, int>(input[0], input[1]);
                }
                Array.Sort(points, (x, y) => x.Item1.CompareTo(y.Item1));
                var minX = points[0].Item1;
                var maxX = points[n - 1].Item1;
                Array.Sort(points, (x, y) => x.Item2.CompareTo(y.Item2));
                var minY = points[0].Item2;
                var maxY = points[n - 1].Item2;
                var can = true;
                //if (minX == maxX || minY == maxY)
                //{
                //    sw.WriteLine("NO");
                //    continue;
                //}
                for (var i = 0; i < n; i++)
                {
                    var isAny = false;
                    if (points[i].Item1 == minX)
                    {
                        isAny = true;
                        if (!(points[i].Item2 >= minY && points[i].Item2 <= maxY))
                        {
                            can = false;
                            break;
                        }
                    }
                    if (points[i].Item1 == maxX)
                    {
                        isAny = true;
                        if (!(points[i].Item2 >= minY && points[i].Item2 <= maxY))
                        {
                            can = false;
                            break;
                        }
                    }
                    if (points[i].Item2 == minY)
                    {
                        isAny = true;
                        if (!(points[i].Item1 >= minX && points[i].Item1 <= maxX))
                        {
                            can = false;
                            break;
                        }
                    }
                    if (points[i].Item2 == maxY)
                    {
                        isAny = true;
                        if (!(points[i].Item1 >= minX && points[i].Item1 <= maxX))
                        {
                            can = false;
                            break;
                        }
                    }
                    if (!isAny)
                    {
                        can = false;
                        break;
                    }
                }

                if (can)
                {
                    sw.WriteLine("YES");
                }
                else
                {
                    sw.WriteLine("NO");
                }
            }
        }
    }
}

internal class InputReader : IDisposable
{
    private bool isDispose;
    private readonly TextReader sr;

    public InputReader(TextReader stream)
    {
        sr = stream;
    }

    public void Dispose()
    {
        Dispose(true);
        GC.SuppressFinalize(this);
    }

    public string NextString()
    {
        var result = sr.ReadLine();
        return result;
    }

    public int NextInt32()
    {
        return Int32.Parse(NextString());
    }

    public long NextInt64()
    {
        return Int64.Parse(NextString());
    }

    public string[] NextSplitStrings()
    {
        return NextString()
            .Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);
    }

    public T[] ReadArray<T>(Func<string, CultureInfo, T> func)
    {
        return NextSplitStrings()
            .Select(s => func(s, CultureInfo.InvariantCulture))
            .ToArray();
    }

    public T[] ReadArrayFromString<T>(Func<string, CultureInfo, T> func, string str)
    {
        return
            str.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries)
                .Select(s => func(s, CultureInfo.InvariantCulture))
                .ToArray();
    }

    protected void Dispose(bool dispose)
    {
        if (!isDispose)
        {
            if (dispose)
                sr.Close();
            isDispose = true;
        }
    }

    ~InputReader()
    {
        Dispose(false);
    }
}