using System;
using System.Collections.Generic;
using System.IO;
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 */
        int q = Convert.ToInt32(Console.ReadLine());
        
        while (q != 0) {
            int n = Convert.ToInt32(Console.ReadLine());
            int [,] points = new int[n,2];
            
            int xMin = Int32.MaxValue;
            int xMax = Int32.MinValue;
            int yMin = Int32.MaxValue;
            int yMax = Int32.MinValue;
            
            for (int i = 0; i < n; i++) {
                string [] tokens = Console.ReadLine().Split(' ');                
                points[i,0] = Convert.ToInt32(tokens[0]);
                points[i,1] = Convert.ToInt32(tokens[1]);     
                
                if (points[i,0] < xMin)
                    xMin = points[i,0];
                if (points[i,0] > xMax)
                    xMax = points[i,0];
                    
                if (points[i,1] < yMin)
                    yMin = points[i,1];
                if (points[i,1] > yMax)
                    yMax = points[i,1];
            }
            
            bool result = true;
            for (int i = 0; i < n; i++) {
                if (points[i,0] != xMin && points[i,0] != xMax && points[i,1] != yMin && points[i,1] != yMax) {
                    result = false;
                    break;
                }
                    
            }
            
            if (result)
                Console.WriteLine("YES");
            else 
                Console.WriteLine("NO");
            
            q--;
        }
    }
}