import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

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];
            int xmax=0,xmin=0,ymax=0,ymin=0;
            for(int j=0;j<n;j++)
            {
                x[j]=sc.nextInt();
                y[j]=sc.nextInt();
                if(xmin>x[j])
                    xmin=x[j];
                if(xmax<x[j])
                    xmax=x[j];
                if(ymin>y[j])
                    ymin=y[j];
                if(ymax<y[j])
                    ymax=y[j];
            }
            boolean c=true;
            for(int j=0;j<n;j++)
            {
                if(((x[j]==xmax)&&(y[j]<=ymax)&&(y[j]>=ymin))||((x[j]==xmin)&&(y[j]<=ymax)&&(y[j]>=ymin))||((y[j]==ymax)&&(x[j]<=xmax)&&(x[j]>=xmin))||((y[j]==ymin)&&(x[j]<=xmax)&&(x[j]>=xmin)))
                    c=c;
                else
                    c=false;
            }
            if(c)
                System.out.println("YES");
            else
                System.out.println("NO");
        }
    }
}