using System;

class Solution
{
    static void Main()
    {
        int q = int.Parse(Console.ReadLine());
        while (q-- > 0)
        {
            int n = int.Parse(Console.ReadLine());
            int[] x = new int[n];
            int[] y = new int[n];
            int minX = 100000, maxX = -100000;
            int minY = 100000, maxY = -100000;

            for (int i = 0; i < n; i++)
            {
                string[] t = Console.ReadLine().Split(' ');
                x[i] = int.Parse(t[0]);
                y[i] = int.Parse(t[1]);

                if (minX > x[i]) minX = x[i];
                if (maxX < x[i]) maxX = x[i];

                if (minY > y[i]) minY = y[i];
                if (maxY < y[i]) maxY = y[i];
            }

            bool result = true; //(maxX != minX) && (maxY != minY);

            //if (result)
            //{
                for (int i = 0; i < n; i++)
                {
                    result &= (x[i] == minX && y[i] >= minY && y[i] <= maxY)
                        || (x[i] == maxX && y[i] >= minY && y[i] <= maxY)
                        || (y[i] == minY && x[i] >= minX && x[i] <= maxX)
                        || (y[i] == maxY && x[i] >= minX && x[i] <= maxX);

                    if (!result) break;
                }
            //}

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