import java.io.*;
import java.util.*;
import java.math.*;
 
public class hack42Q2
{
    public static void main(String[] args) throws IOException
    {
        FastScanner obj = new FastScanner();
        out = new PrintWriter(new BufferedOutputStream(System.out));
		int q = obj.nextInt();
		while(q-->0)
		{
			int n = obj.nextInt();
			int x = obj.nextInt();
			int y = obj.nextInt();
			String ans="";
			while(n-->1)
			{
				
				int x2 = obj.nextInt();
				int y2 = obj.nextInt();
				if(x2==x || y2==y)
					ans= "YES";
				else
				{
					ans="NO";
					break;
				}
			}
			out.println(ans);
		}
			      
        out.close();
   }
   

   //-----------PrintWriter for faster output---------------------------------
   public static PrintWriter out;
      
   //-----------FastScanner class for faster input----------
   public static class FastScanner {
        BufferedReader br;
        StringTokenizer tokenizer;
 
        public FastScanner() throws IOException {
            br = new BufferedReader(new InputStreamReader(System.in));
            tokenizer = new StringTokenizer(br.readLine().trim());
        }
 
        String next() {
            while (tokenizer == null || !tokenizer.hasMoreElements()) {
                try {
                    tokenizer = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                    }
            }
          return tokenizer.nextToken();
        }
 
        int nextInt() {
            return Integer.parseInt(next());
        }
 
        long nextLong() {
            return Long.parseLong(next());
        }
 
        double nextDouble() {
            return Double.parseDouble(next());
        }
      
        int[] nextIntArray() throws IOException {
            String[] line = br.readLine().trim().split(" ");
            int[] out = new int[line.length];
            
            for (int i = 0; i < line.length; i++) {
                out[i] = Integer.valueOf(line[i]);
            }
            return out;
        }
        
        BigInteger nextBigInteger() throws IOException {
            return new BigInteger(next());
        }
        
        String nextLine(){
            String str = "";
	        try {
	            str = br.readLine();
	        } catch (IOException e) {
	            e.printStackTrace();
	        }
	        return str;
        }

   }
   //--------------------------------------------------------
}