import java.util.*;
class PointsInARectangle
{
	public static void main(String[] args)
	 { Scanner s=new Scanner(System.in);
		int t=s.nextInt();
		while (t--!=0) 
		{  int q=s.nextInt();
           int[] xArray=new int[q];
           int[] yArray=new int[q];
           for(int i=0;i<q;i++)
           { xArray[i]=s.nextInt();
              yArray[i]=s.nextInt();
           }
           int xmin=99999,ymin=99999,xmax=-99999,ymax=-99999;
            for(int i=0;i<q;i++)
            {  if(xArray[i]>xmax)xmax=xArray[i]; 
                if(xArray[i]<xmin)xmin=xArray[i];
                if(yArray[i]>ymax)ymax=yArray[i];
                if(yArray[i]<ymin)ymin=yArray[i];
            }	
            boolean flag=true;
            for(int i=0;i<q;i++)
            {   if(xArray[i]==xmin||xArray[i]==xmax||yArray[i]==ymin||yArray[i]==ymax)
            	{}
            	else
            	{
            		flag=false;break;
            	}

            }
            if(flag) System.out.println("YES");
            else System.out.println("NO");



		}
	}
}