import java.util.Scanner;
import java.util.TreeSet;

public class Solution {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int T = sc.nextInt();
        for (int t = 0; t < T; t++) {
            TreeSet<Integer> x = new TreeSet<>();
            TreeSet<Integer> y = new TreeSet<>();
            int n = sc.nextInt();
            int[][] pts = new int[n][2];
            for (int i = 0; i < n; i++) {
                int pX = sc.nextInt();
                int pY = sc.nextInt();

                pts[i] = new int[] {pX, pY};

                x.add(pX);
                y.add(pY);
            }

            boolean OK = true;
            for (int[] pt : pts) {
                if (pt[0] != x.first() && pt[0] != x.last() && pt[1] != y.first() && pt[1] != y.last()) {
                    OK = false;
                    break;
                }
            }

            System.out.println(OK ? "YES" : "NO");
        }
    }

}