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 sc=new Scanner(System.in);
   int q=sc.nextInt();
    while(q--!=0){
      
        int n=sc.nextInt();
        int[][] a=new int[n][2];
        for( int i=0;i<n;i++){
            a[i][0]=sc.nextInt();
            a[i][1]=sc.nextInt();
        }
        int x1=-10001,x2=10001,y1=-10001,y2=10001;
        for(int i=0;i<n;i++){
            if(x1<a[i][0])
                x1=a[i][0];
            if(x2>a[i][0])
                x2=a[i][0];
            if(y1<a[i][1])
                y1=a[i][1];
            if(y2>a[i][1])
                y2=a[i][1];
        }
      int i=0;
        for( i=0;i<n;i++){
            if(a[i][0]!=x1 && a[i][0]!=x2 && a[i][1]!=y1 && a[i][1]!=y2){
             System.out.println("NO");
                break;
            }
        }
        if(i==n)
          System.out.println("YES");
            
    }    
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
    }
}