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

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 q=sc.nextInt();
        
        
        for(int i=0;i<q;i++)
            {
            int n=sc.nextInt();
            Set<Integer> s1=new HashSet<>();
             Set<Integer> s2=new HashSet<>();
            for(int j=0;j<n;j++)
                {
               int x=sc.nextInt();
            int y=sc.nextInt();
            s1.add(x);
            s2.add(y); 
            }
            int x1=s1.size();
            int y1=s2.size();
            if(x1<3&&y1<3)
                System.out.println("YES");
            else
                System.out.println("NO");
                
            
            
        }
        
        
    }
}