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

public class Solution {

    public static void main(String[] args) {
        int q;
        int n;
        Set x_set = new HashSet();
        Set y_set = new HashSet();
        Scanner input = new Scanner(System.in);
        q = input.nextInt();
        for(int i = 0; i < q; i++)
        {
            n = input.nextInt();
            for(int j=0; j<n; j++)
            {
                x_set.add(input.nextInt());
                y_set.add(input.nextInt());
            }
            if(x_set.size() == 2 && y_set.size() == 2)
                System.out.println("YES");
            else
                System.out.println("NO");
        }
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
    }
}