import java.io.*;
import java.util.*;

public class Solution {

    public static void main(String[] args) {
    
        	
	Scanner obj=new Scanner(System.in);
	int t=obj.nextInt();
	
	int n;
	int x1=0,y1=0;
	
	boolean flag;
	
	while(t>=1)
	{
		
	n=obj.nextInt();
	int x2=0,y2=0;
 flag=true;
	
	for(int i=1;i<=n;i++)
	{
		
		if(i==1)
		{
			x1=obj.nextInt();
			y1=obj.nextInt();
			
			
		}
		
		else{
			x2=obj.nextInt();
			y2=obj.nextInt();
			
			if(x2-x1!=0&&y2-y1!=0)
			{
				
				flag=false;
	      			
			}
			
			
		}
		
		
		
	}
		if(!flag)
			System.out.println("NO");
		else
			System.out.println("YES");
	
		
		
		
		
		
		t--;
	}
	
        
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
    }
}