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) {
       Scanner scan = new Scanner(System.in);
       int q = scan.nextInt();
       for(int u =0 ; u < q ; u++){
           int p = scan.nextInt();
           int[] x= new int[p];
           int[] y= new int[p];
           int minx =0, miny=0, maxx=0, maxy=0;
           for(int i=0; i < p ; i++){
               x[i]= scan.nextInt();
               y[i] = scan.nextInt();
               if (i==0){
                   minx =x[i];
                   maxx=x[i];
                   miny = y[i];
                   maxy = y[i];
               }
               
               
               if(minx>x[i]){
                   minx=x[i];
               }if(miny>y[i]){
                   miny=y[i];
               }
               if(maxx<x[i]){
                   maxx = x[i];
                   
               }
               if(maxy<y[i]){
                   maxy = y[i];
               }
           }
         
                                    
                  
                boolean isTrue = true;                 
                for(int t=0; t < p ; t++){
                    if(x[t]>=minx && x[t]<=maxx && (y[t]==miny || y[t]==maxy)){
                       continue;
                    }else if(y[t]>=miny && y[t]<=maxy && (x[t]==minx || x[t]==maxx)){
                        continue;
                    }else{
                        isTrue =false;
                        break;
                    }
                    
                }
                                    
               if(isTrue){
                   System.out.println("YES");
               }else{
                   System.out.println("NO");
               }
           
           
           
           
       } 
    }
}