import java.io.*;
import java.math.BigInteger;
import java.util.*;



public class B
{
    String line;
    StringTokenizer inputParser;
    BufferedReader is;
    FileInputStream fstream;
    DataInputStream in;
    String FInput="";
    
    void openInput(String file)
    {

            if(file==null)is = new BufferedReader(new InputStreamReader(System.in));//stdin
            else
            {
                    try{
            
                            
                    fstream = new FileInputStream(file);
                    in = new DataInputStream(fstream);
                    is = new BufferedReader(new InputStreamReader(in));
                    }catch(Exception e)
                    {
                            System.err.println(e);
                    }
            }

    }
    
    void readNextLine()
	{
		try {
			line = is.readLine();
			inputParser = new StringTokenizer(line, " ,\t");
			//System.err.println("Input: " + line);
		} catch (IOException e) {
			System.err.println("Unexpected IO ERROR: " + e);
		}	
		catch (NullPointerException e)
		{
			line=null;
			
		}
		
	}
    
    long NextLong()
    {
            String n = inputParser.nextToken();
            
            long val = Long.parseLong(n);
            
             return val;
    }
    
    int NextInt()
    {
            String n = inputParser.nextToken();
            int val = Integer.parseInt(n);
            
            //System.out.println("I read this number: " + val);
            return val;
    }
    
    double NextDouble()
    {
            String n = inputParser.nextToken();
            double val = Double.parseDouble(n);
            
            //System.out.println("I read this number: " + val);
            return val;
    }
    
    String NextString()
    {
            String n = inputParser.nextToken();
            return n;
    }
    
    void closeInput()
    {
            try {
                    is.close();
            } catch (IOException e) {
                    System.err.println("Unexpected IO ERROR: " + e);
            }
                    
    }
    
    public static void main(String [] argv)
    {
            //String filePath="circles.in";
            String filePath=null;
            if(argv.length>0)filePath=argv[0];
            new B(filePath);
            
    }
    
    public B(String inputFile)
    {
    	openInput(inputFile);
		readNextLine();
		int T=NextInt();
		StringBuilder sb = new StringBuilder();
		for(int t=1; t<=T; t++)
		{
			readNextLine();
			int N=NextInt();
			HashSet <Integer> x = new HashSet<Integer>();
			HashSet <Integer> y = new HashSet<Integer>();
			int [] xx = new int[N];
			int [] yy = new int[N];
			for(int i=0; i<N; i++)
			{
				readNextLine();
				xx[i]= NextInt();
				yy[i]= NextInt();
				x.add(xx[i]);
				y.add(yy[i]);
			}
			boolean ok=false;
			out:for(int X1:x)
				for(int X2:x)
					for(int Y2:y)
						for(int Y1:y)
						{
							ok=true;
							for(int i=0; i<N; i++)
							{
								ok=false;
								if((xx[i]==X1||xx[i]==X2)&&(yy[i]<=Y2&&yy[i]>=Y1))ok=true;
								if((yy[i]==Y1||yy[i]==Y2)&&(xx[i]<=X2&&xx[i]>=X1))ok=true;
								if(!ok)break;
							}
							if(ok)
								break out;
						}
			if(ok)sb.append("YES\n");
			else sb.append("NO\n");
		}
		System.out.print(sb);
		
		closeInput();		
	}
    
}