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();
            int[] x = new int[n];
            int[] y = new int[n];
            for (int j = 0; j < n; j++) 
            {
                x[j] = sc.nextInt();
                y[j] = sc.nextInt();
            }
            int xmax = Integer.MIN_VALUE;
            int xmin = Integer.MAX_VALUE;
            for (int elem : x) 
            {
                if (elem > xmax) {xmax = elem;}
                if (elem < xmin) {xmin = elem;}
            }
            int ymax = Integer.MIN_VALUE;
            int ymin = Integer.MAX_VALUE;
            for (int elem : y) 
            {
                if (elem > ymax) {ymax = elem;}
                if (elem < ymin) {ymin = elem;}
            }
            boolean yes = true;
            for (int k = 0; k < n; k++) 
            {
                if (x[k] != xmax && x[k] != xmin && y[k] != ymax && y[k] != ymin) 
                {
                    yes = false;
                    break;
                }
            }
            System.out.println(yes ? "YES" : "NO");
        }
    }
}