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) {
        Scanner in=new Scanner(System.in);
        int q=in.nextInt();
        String ans="YES";
        while(q-->0){
            int points=in.nextInt();
            int x[]=new int[points];
            int y[]=new int[points];
            int max_x=Integer.MIN_VALUE;
            int max_y=Integer.MAX_VALUE;
            for(int i=0;i<points;i++){
                int _x=in.nextInt();
                int _y=in.nextInt();
                x[i]=_x;
                y[i]=_y;
                if(_x==0)
                    max_y=Math.max(max_y,_y);
                if(_y==0)
                   max_x=Math.max(max_x,_x); 
            }
            for(int i=0;i<points;i++){
                if(x[i]!=0&&y[i]!=0){
                    if(x[i]==max_x||y[i]==max_y)
                        ans="YES";
                    else{
                        ans="NO";
                        break;
                    }
                }
            }
            System.out.println(ans);
        }
    }
}