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) {
        int q,n;
        int[] x=new int[10];
        int[] y=new int[10];
        int temp1=1,temp2=1;
        int maxx=0,maxy=0;
        Scanner sc=new Scanner(System.in);
        q=sc.nextInt();
        while(q!=0){
            int test=1;
            n=sc.nextInt();
            for(int i=0;i<n;i++){
                x[i]=sc.nextInt();
                if(temp1<x[i]) maxx=x[i];
                else maxx=temp1;
                y[i]=sc.nextInt();
                if(temp2<y[i]) maxy=y[i];
                else maxy=temp2;
            }
           
           for(int i=0;i<n;i++){
               if((x[i]==0 && y[i]<=maxy)||(x[i]<=maxx && y[i]==0)||(x[i]==maxx && y[i]== maxy)) continue;
               else{ test=0; break; }
           }
           if(test==0){ System.out.println("NO"); }
           else System.out.println("YES");
        }
        sc.close();
    }
}