using System;
using System.Linq;
using System.Collections.Generic;
using System.IO;
class Solution
{
    static void Main(String[] args)
    {
        int tc = Convert.ToInt32(Console.ReadLine());
        for (int t = 0; t < tc; t++)
        {
            int nop = Convert.ToInt32(Console.ReadLine());
            int[] xs = new int[nop];
            int[] ys = new int[nop];

            for (int i = 0; i < nop; i++)
            {
                int[] ps = Array.ConvertAll<string, int>(Console.ReadLine().Split(' '), Convert.ToInt32);
                xs[i] = ps[0];
                ys[i] = ps[1];
            }

            int minx = xs.Min();
            int maxx = xs.Max();

            int miny = ys.Min();
            int maxy = ys.Max();

            bool result = true;
            for (int i = 0; i < nop; i++)
            {
                int x = xs[i];
                int y = ys[i];

                if (x >= minx && x <= maxx && (y == miny || y == maxy))
                    continue;
                else if (y >= miny && y <= maxy && (x == maxx || x == minx))
                    continue;
                else
                {
                    result = false;
                    break;
                }
            }
            Console.WriteLine(result ? "YES" : "NO");

        }
    }
}