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

public class Solution {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int q = sc.nextInt();
        for(int i=0; i<q; i++){
            boolean val= false;
            int n = sc.nextInt();
            int x = sc.nextInt();
            int y = sc.nextInt();
            for(int j=1; j<n; j++){
                int x1 = sc.nextInt();
                int y1 = sc.nextInt();
                if(x1==x || y1 ==y){
                    val = true;
                    
                }
                else val =false;
                break;
            }
            if(val==true){
                System.out.println("YES");
            }
            else
                System.out.println("NO");
        }
    }
}