import java.io.*;
import java.util.*;

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();
        while(q>0)
            {
            int n=in.nextInt();
            int a[][]=new int[n][2];
            
            int max1=0;
            int min1=0;
            
            for(int i=0;i<n;i++)
                {
                for(int j=0;j<2;j++)
                    {
                    a[i][j]=in.nextInt();
                    max1=(int)Math.max(max1,a[i][j]);
                    min1=(int)Math.min(min1,a[i][j]);
            }
            
            }
            
            
            int flag=0;
            
             for(int i=0;i<n;i++)
                {
                for(int j=0;j<1;j++)
                    {
                    if(a[i][j]==min1 || a[i][j]==max1)
                        {
                        if(a[i][j+1]>=min1 && a[i][j+1]<=max1)
                            {
                            flag++;
                        }
                    }
                    
                    
                    
                }
             }
            
             
            if(flag==n)
                System.out.println("YES");
            
            
            
            else
                System.out.println("NO");
            
            
            
            
            q--;
        }
        
        
    }
}