using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;

class Solution {
    static void Main(String[] args) {
       int q = int.Parse(Console.ReadLine());
        for (int i=0; i<q; i++){
            Solve();
        }
    }
    
    static void Solve(){
        int n = int.Parse(Console.ReadLine());
        int[,] points= new int[n,2];
        int minX = int.MaxValue;
        int maxX = int.MinValue;
        int minY = int.MaxValue;
        int maxY = int.MinValue;
        for(int i=0; i<n; i++){
            var arr = Console.ReadLine().Split(' ').Select(a => int.Parse(a)).ToArray();
            int x = arr[0];
            int y = arr[1];
            points[i,0] = x;
            points[i,1] = y;
            minX = Math.Min(minX, x);
            maxX = Math.Max(maxX, x);
            minY = Math.Min(minY, y);
            maxY = Math.Max(maxY, y);
        }
        
        for(int i=0; i<n; i++){
            if(!(points[i,0] == minX ||
                 points[i,0] == maxX ||
                 points[i,1] == minY ||
                 points[i,1] == maxY)){
                Console.WriteLine("NO");
                return;
            }
        }
        Console.WriteLine("YES");
    }
}