using System;
using System.Collections.Generic;
using System.IO;
class Solution {
    static void Main(String[] args) {
        int tc = Convert.ToInt32(Console.ReadLine());
        int n;
        int[] ar;
        int[] x, y;
        int maxx=0, maxy=0, minx=0, miny=0;

        for (int ti = 0; ti < tc; ti++)
        {
            n = Convert.ToInt32(Console.ReadLine());
            x = new int[n];
            y = new int[n];
            
            for(int i=0;i<n;i++)
            {
                ar = Array.ConvertAll(Console.ReadLine().Split(), Int32.Parse);
                x[i] = ar[0];
                y[i] = ar[1];
                
                if(i==0)
                {
                    minx = x[0];
                    miny = y[0];
                    maxx = x[0];
                    maxy = y[0];
                }
                else
                {
                    if(x[i]>maxx) maxx = x[i];                    
                    if(y[i]>maxy) maxy = y[i];                    
                    if(x[i]<minx) minx = x[i];                    
                    if(y[i]<miny) miny = y[i];                    
                }
            }
            
            bool pass = true;
            for(int i=0;i<n;i++)
            {
                int c = ((x[i]==minx || x[i]==maxx)?1:0) + ((y[i]==miny || y[i]==maxy)?1:0);
                if(c==0)
                {
                    pass = false;
                    break;
                }
            }
            
            Console.WriteLine(pass ? "YES" : "NO");
        }
    }
}