using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
class Solution
{
    static void Main(String[] args)
    {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution */

        var q = int.Parse(Console.ReadLine());
        for (var qi = 0; qi < q; qi++)
        {
            var n = int.Parse(Console.ReadLine());
            var points = Enumerable.Range(0, n).Select(ni => Console.ReadLine().Split(' ').Select(int.Parse).ToArray()).ToArray();

            var xMax = points.Max(p => p[0]);
            var xMin = points.Min(p => p[0]);

            var yMax = points.Max(p => p[1]);
            var yMin = points.Min(p => p[1]);

            var YES = points.All(p => 
                ((p[0] == xMin || p[0] == xMax) && (p[1] >= yMin || p[1] <= yMax))
                ||
                ((p[1] == yMin || p[1] == yMax) && (p[0] >= xMin || p[0] <= xMax))
            );


            Console.WriteLine(YES ? "YES" : "NO");
        }

    }
}