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 in = new Scanner(System.in);
        int q=in.nextInt();
        int n;
        for(int i=0;i<q;i++){
             n=in.nextInt();
             int[] x= new int[n];
             int[] y= new int[n];
             int tempx1=0,tempx2=0,tempy1,tempy2=0,f=0;
             for(int j=0;j<n;j++){
                 x[j]=in.nextInt();
                 y[j]=in.nextInt();
             }
            tempx1=x[0];tempy1=y[0]; tempx2=x[0];tempy2=y[0];
            for(int j=1;j<n;j++){
               if(tempx1<x[j])
                   tempx1=x[j];
                if(tempy1<y[j])
                    tempy1=y[j];
                if(tempx2>x[j])
                   tempx2=x[j];
                if(tempy2>y[j])
                    tempy2=y[j];
                   
               }
            for(int j=0;j<n;j++){
                if(x[j]!=tempx1&&x[j]!=tempx2&&y[j]!=tempy1&&y[j]!=tempy2)
                    f=1;
            }
           // System.out.println(tempx1+"-"+tempy1+"-"+tempx2+"-"+tempy2);
            if(f==0)
                System.out.println("YES");
            else
                System.out.println("NO");
        }
    }
}