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);
        int t=sc.nextInt();
        while(t>0)
            {
            int n=sc.nextInt();
            boolean a=true;
              int[] x=new int[n];
              int[] y=new int[n];
            for(int k=0;k<n;k++)
                {
                 x[k]=sc.nextInt();
                 y[k]=sc.nextInt();
                
            }
            int minx=10000,maxx=-10000,miny=10000,maxy=-1000;
            for(int i=0;i<n;i++)
                {
                if(x[i]<minx)
                    minx=x[i];
                if(x[i]>maxx)
                    maxx=x[i];
                if(y[i]<miny)
                    miny=y[i];
                if(y[i]>maxy)
                    maxy=y[i];
            }
            for(int i=0;i<n;i++)
                {
                if(x[i]!=minx && x[i]!=maxx && y[i]!=miny && y[i]!=maxy)
                    a=false;
            }
            if(a)
                System.out.println("YES");
            else
                System.out.println("NO");
                
            
            t--;
        }
    }
}