import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    public static void main(String[] args) {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
        Scanner sc=new Scanner(System.in);
       // Point points []=new Point[n];
        int q=sc.nextInt();
        int n;
        LinkedList<Integer> xa=new LinkedList<Integer>();
        LinkedList<Integer> ya=new LinkedList<Integer>();
        for(int i=0;i<q;i++){
            n=sc.nextInt();
           // LinkedList<Point> points=new LinkedList<Point>();
            
            
            for(int j=0;j<n;j++){
                int x=sc.nextInt();
                int y=sc.nextInt();
                xa.add(x);
                ya.add(y);
                
                
            }
             int minx=min(xa);
         int miny=min(ya);
         int maxx=max(xa);
         int maxy=max(ya);
        boolean flag=true;
          //  System.out.println(minx);
          //  System.out.println(maxx);
           // System.out.println(miny);
          //  System.out.println(maxy);
       for(int k=0;k<xa.size();k++){
           int x=xa.get(k);
           int y=ya.get(k);
           //System.out.println(x);
           //System.out.println(y);
           if((x==minx&&miny<=y&&y<=maxy)||(x==maxx&&miny<=y&&y<=maxy)||(y==miny&&minx<=x&&x<=maxx)||(y==maxy&&minx<=x&&x<=maxx)){
               
           }
           else{
               flag=false;
               break;
           }
               
       }
        if(flag){
            System.out.println("YES");
        }
        else{
            System.out.println("NO");
        }
        
            
        }
       
        
    }
    static int max(LinkedList<Integer> a){
        int temp=Integer.MIN_VALUE;
        for(int i=0;i<a.size();i++){
            if(a.get(i)>temp)
                temp=a.get(i);
        }
        return temp;
    }
     static int min(LinkedList<Integer> a){
        int temp=Integer.MAX_VALUE;
        for(int i=0;i<a.size();i++){
            if(a.get(i)<temp)
                temp=a.get(i);
        }
        return temp;
    }
    
}