import java.io.*;
import java.util.*;

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);
        int q=sc.nextInt();
        for(int i=0;i<q;i++)
            {
            int n=sc.nextInt();
            int x[]=new int[n];
            int y[]=new int[n];
            int miny=10000;
            int minx=10000;
            int maxx=-10000;
            int maxy=-10000;
            for(int j=0;j<n;j++)
                {
                x[j]=sc.nextInt();
                y[j]=sc.nextInt();
                if(x[j]<=minx)
                    minx=x[j];
                if(x[j]>=maxx)
                    maxx=x[j];
                if(y[j]<=miny)
                    miny=y[j];
                if(y[j]>=maxy)
                    maxy=y[j];
                    
                
            }
            boolean check=false;
            for(int j=0;j<n;j++)
                {
                if(((x[j]==minx||x[j]==maxx)&&(y[j]>=miny&&y[j]<=maxy))||((y[j]==miny||y[j]==maxy)&&(x[j]>=minx&&x[j]<=maxx)))
                   check= true;
                   else
                   {
                       check=false;
                       break;
                   }
                   }
                   if(check==true)
                   System.out.println("YES");
                   else
                   System.out.println("NO");
                   
            
            
        }
    }
}