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 s = new Scanner(System.in);
        int q = s.nextInt();
        for(int j=0;j<q;j++){
            int n= s.nextInt();
            int arr[][] = new int[n][2];
            for(int i=0;i<n;i++){
                int x = s.nextInt();
                int y = s.nextInt();
                arr[i][0]=x;
                arr[i][1]=y;
            }
            
            boolean flag = checkRectangle(arr,n);
            if(flag){
                System.out.println("YES");
            }else{
                System.out.println("NO");
            }
        }
    }
    
    static boolean checkRectangle(int arr[][],int n){
        if(n<=2){
            return true;
        }else{
            int x_max = Integer.MIN_VALUE;
            int x_min = Integer.MAX_VALUE;
            int y_max = Integer.MIN_VALUE;
            int y_min = Integer.MAX_VALUE;
            for(int i=0;i<n;i++){
                if(arr[i][0]>x_max){
                    x_max = arr[i][0];
                }if(arr[i][0]<x_min){
                    x_min = arr[i][0];
                }if(arr[i][1]>y_max){
                    y_max = arr[i][1];
                }if(arr[i][1]<y_min){
                    y_min = arr[i][1];
                }
            }
           
            boolean flag = true;
            for(int i=0;i<n;i++){
                if((arr[i][0]!=x_min && arr[i][1]!=y_min)&&(arr[i][0]!=x_max && arr[i][1]!=y_max)){
                   
                    flag = false; 
                }
            }
            return flag;
        }
        
    }
}