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();
        while(q-->0)
            {
            int n = sc.nextInt();
            int []x = new int[n];
            int []y = new int[n];
            for(int i=0;i<n;i++)
                {
                x[i] = sc.nextInt();
                y[i] = sc.nextInt();
            }
            int count=0;
            for(int i=0;i<n-1;i++)
                {
                if(x[i]!= x[i+1] && y[i] !=y[i+1] && y[i]!= x[i+1] && x[i] !=y[i+1])
                    {
                    count=1;
                    break;
                }
            }
            if(count==1)
                System.out.println("NO");
            else
                System.out.println("YES");
        }
    }
}