using System;
using System.Collections.Generic;
using System.IO;
class Solution {
    static void Main(String[] args) {
        string qs = Console.ReadLine();
        int q = Convert.ToInt32(qs);
        bool yes = true;       
        for (int qi=0; qi<q; qi++) {
            int x_max = Int32.MinValue;
            int y_max = Int32.MinValue;
            int x_min = Int32.MaxValue;
            int y_min = Int32.MaxValue;
           
            string ns = Console.ReadLine();
            int n = Convert.ToInt32(ns);
            int[,] arr = new int[2, n];
            for (int ni=0; ni<n; ni++) {
                string[] a_temp = Console.ReadLine().Split(' ');
                int x = Convert.ToInt32(a_temp[0]);
                int y = Convert.ToInt32(a_temp[1]);
                if (x > x_max) x_max = x;
                if (y > y_max) y_max = y;
                if (x < x_min) x_min = x;
                if (y < y_min) y_min = y;
                arr[0,ni] = x;
                arr[1,ni] = y;
            }
 
            yes = true;
            /*
            if (x_max == x_min || y_max == y_min) {
                yes = false;
            if (x_max - x_min == y_max - y_min) {
                yes = false;
            } else {*/
                for (int ni=0; ni<n; ni++) {
                    if ((arr[0,ni] > x_min && arr[0,ni] < x_max) && (arr[1,ni] > y_min && arr[1,ni] < y_max)) {
                        yes = false;
                        break;
                    }
                }                    
            //}
            if (yes) Console.WriteLine("YES");
            else  Console.WriteLine("NO");
        }
    }
}