import java.util.Arrays;
import java.util.Scanner;

public class POAR {
    public static void main(String[] arg) {
        new POAR().testCPS();
    }
    private void testCPS() {
        Scanner scan = new Scanner(System.in);
        long T = scan.nextLong();
        for (long t = 0; t < T; t++) {
            System.out.println(CPS(scan));
        }
    }
    private String CPS(Scanner scan) {
        int n = scan.nextInt();
        if (n == 1) {
            scan.nextLong();
            scan.nextLong();
            return "YES";
        }
        long x = scan.nextLong();
        long y = scan.nextLong();
        long miX = x;
        long maX = x;
        long miY = y;
        long maY = y;
        Point[] a = new Point[n];
        a[0] = new Point(x, y);
        for (int i = 1; i < n; i++) {
            x = scan.nextLong();
            y = scan.nextLong();
            miX = Math.min(miX, x);
            maX = Math.max(maX, x);
            miY = Math.min(miY, y);
            maY = Math.max(maY, y);
            a[i] = new Point(x, y);
        }
        for (int i = 0; i < n; i++) {
            if (a[i].x == miX || a[i].x == maX) {
                if (!(a[i].y <= maY) || !(a[i].y >= miY)) {
                    return "NO";
                }
            } else if (a[i].y == miY || a[i].y == maY) {
                if (!(a[i].x <= maX) && !(a[i].x >= miX)) {
                    return "NO";
                }
            } else {
                return "NO";
            }
        }
        return "YES";
    }
    private class Point {
        long x;
        long y;

        public Point() {

        }
        public Point(long x, long y) {
            this.x = x;
            this.y = y;
        }
    }
}