import java.util.*;
import java.math.*;
public class Hack42_2 {
	
 static Scanner sc = new Scanner(System.in);
 static int mod = 1000000007;	
 
 public static void main(String[] args)
 {
	 int q = ni();
	 TCLOOP:
	 while(q-->0)
	 {
		 int n = ni();
		 int[] x = new int[n];
		 int[] y = new int[n];
		 for(int i=0;i<n;i++)
		 {
			 x[i]=ni();
			 y[i]=ni();
		 }
		 boolean p = true;
		 int x1=Integer.MAX_VALUE,x2=Integer.MIN_VALUE,y1=Integer.MAX_VALUE,y2=Integer.MIN_VALUE;
		 for(int i=0;i<n;i++)
		 {
			 x1 = Math.min(x1,x[i]);
			 x2 = Math.max(x2,x[i]);
			 y1 = Math.min(y1,y[i]);
			 y2 = Math.max(y2,y[i]);
		 }
		 for(int i=0;i<n;i++)
		 {
			 if(x[i]==x1 || x[i]==x2 || y[i]==y1 || y[i]==y2)
				 continue;
			 else
			 {
				 p = false;
				 break;
			 }
		 }
		 System.out.println(p ? "YES":"NO");
	 }
 }
 
 static long[] la(int x)
 {
	 long[] a = new long[x];
	 for(int i=0;i<x;i++)
		 a[i]=sc.nextLong();
	 return a;
 }
 
 static int[] ia(int x)
 {
	 int[] a = new int[x];
	 for(int i=0;i<x;i++)
		 a[i]=sc.nextInt();
	 return a;
 }
 
 static char[] ca()
 { return sc.next().toCharArray(); }
 
 static int ni()
 { return sc.nextInt();}
 
 static long nl()
 { return sc.nextLong();}
 
 static double nd()
 { return sc.nextDouble();}
 
}