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();
        int n;
        int flag=1;
        int x,y,mx1=99999,mx2=99999,my1=99999,my2=99999,tx,ty;
        for(int i=1;i<=q;i++)
        {
                flag=1;
              n=sc.nextInt();
              
              if(n==1)
              {
                       
                      x=sc.nextInt();
                      y=sc.nextInt();
                      flag=1;
              }
              else if(n>1)
              {
                  
                      for(int j=1;j<=n;j++)
                      {
                            if(j==1)
                            {
                                mx1=sc.nextInt();
                                my1=sc.nextInt();
                            }
                            else if(j==2)
                            {
                                tx=sc.nextInt();
                                ty=sc.nextInt();
                                if(mx1!=tx)
                                {
                                    mx2=tx;
                                   
                                }
                                if(my1!=ty)
                                {
                                    my2=ty;    
                                }
                            }
                            else
                            {
                                tx=sc.nextInt();
                                ty=sc.nextInt();
                                if(mx1==99999)
                                    mx1=tx;
                                else if(mx2==99999)
                                    mx2=tx;
                                    
                                if(my1==99999)
                                    my1=ty;
                                else if(my2==99999)
                                    my2=ty;
                                    
                                if((tx==mx1 || tx==mx2) && (ty<=Math.max(my1,my2) && ty>=Math.min(my1,my2)));
                                if((ty==my1 || ty==my2) && (tx<=Math.max(mx1,mx2) && tx>=Math.min(mx1,mx2)));
                                else
                                    flag=0;
                            }
                      }
              }
            if(flag==1)
                System.out.println("YES");
            else
                System.out.println("NO");
        }
    }
}