import java.util.*;

public class Rect {
   private Point[] pts;

   private int xmax;
   private int xmin;
   private int ymax;
   private int ymin;

   public Rect(Point[] pts) {
      this.pts = pts;

      xmax = Integer.MIN_VALUE;
      ymax = Integer.MIN_VALUE;

      xmin = Integer.MAX_VALUE;
      ymin = Integer.MAX_VALUE;

      for (int i = 0; i < pts.length; i++) {
         xmin = Math.min(xmin, pts[i].x());
	 xmax = Math.max(xmax, pts[i].x());

	 ymin = Math.min(ymin, pts[i].y());
	 ymax = Math.max(ymax, pts[i].y());
      }
   }

   public static void main(String[] args) {
      Scanner sc = new Scanner(System.in);
      int tc = sc.nextInt();

      for (int t = 0; t < tc; t++) {
         int n = sc.nextInt();
	 Point[] pts = new Point[n];

	 for (int i = 0; i < n; i++) {
	    pts[i] = new Point(sc.nextInt(), sc.nextInt());
	 }

         Rect rc = new Rect(pts);
	 if (rc.allPointOnBoundary()) {
	    System.out.println("YES");
	 } else {
	    System.out.println("NO");
	 }
      }
   }

   public boolean allPointOnBoundary() {
      boolean[] all =  new boolean[pts.length];

      // marking 
      for (int i = 0; i < pts.length; i++) {
         Point pt = pts[i];

	 if (pt.x() ==  xmin || pt.x() == xmax) {
	    if (pt.y() >= ymin && pt.y() <= ymax) {
	       all[i] = true;
	    }
	 }


	 if (pt.y() == ymin || pt.y() == ymax) {
	    if (pt.x() >= xmin && pt.x() <= xmax) {
	       all[i] = true;
	    }
	 }
      }

      for (int i = 0; i < pts.length; i++) {
         if (! all[i]) return false;
      }

      return true;
   }
}

class Point {
   private int x;
   private int y;

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

   public int x() {
      return x;
   }

   public int y() {
      return y;
   }
}