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 sn = new Scanner(System.in);
        int q = sn.nextInt();
        for(int i=0;i<q;i++){
            int n = sn.nextInt();
            int[] x = new int[n];
            int[] y = new int[n];
            for(int j=0;j<n;j++){
                x[j] = sn.nextInt();
                y[j] = sn.nextInt();
            }
            int a=0,b=0;
            HashSet<Integer> set = new HashSet<>();
            HashSet<Integer> set1 = new HashSet<>();
        for (int l=0; l<n; l++)
        {
            if (!set.contains(x[l]))
            {
                set.add(x[l]);
                a++;
            }
        }
            for (int k=0; k<n; k++)
        {
            if (!set1.contains(y[k]))
            {
                set1.add(y[k]);
                b++;
            }
        }
            if(a<=2||b<=2)
                System.out.println("YES");
                else System.out.println("NO");
        }
    }
}