import java.util.*; 
import java.math.*;
import java.io.*;
import java.text.DecimalFormat;
import java.math.BigInteger;
public class Solution{
    //static int d=20;
    static long mod=1000000007 ;
    //static HashMap<String,Integer> hm=new HashMap<>(); 
    static ArrayList<ArrayList<Integer>> arr;
    static int size;
    static long[][] fac;
    static long[][] dp;
    static int num,max;
    static int ans=0;
    static HashMap<Integer,Integer> hm;
    public static void main(String[] args)  throws IOException {
        boolean online =false;
        String fileName = "C-large";
        PrintWriter out;
        if (online) {
            s.init(new FileInputStream(new File(fileName + ".in")));
             out= new PrintWriter(new FileWriter(fileName + "out.txt"));
        }
         else {
            s.init(System.in);   
        
            out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
        }
        
        int q=s.ni();
        while(q--!=0){
            int n=s.ni();
            int[][] a=new int[n][2];
            int x1,x2,y1,y2;
            x1=y1=Integer.MAX_VALUE;
            x2=y2=Integer.MIN_VALUE;
            for(int i=0;i<n;i++){
                a[i][0]=s.ni();
                a[i][1]=s.ni();
                x1=Math.min(x1,a[i][0]);
                x2=Math.max(x2,a[i][0]);
                y1=Math.min(y1,a[i][1]);
                y2=Math.max(y2,a[i][1]);

            }
            int flag=0;
            for(int i=0;i<n;i++){
                if(a[i][0]==x1 || a[i][0]==x2 || a[i][1]==y1 || a[i][1]==y2)
                    continue;
                else{
                    flag=1;
                    break;
                }
            }
            if(flag==0)
                out.println("YES");
            else
                out.println("NO");

        }
        out.close();
        
    }
 
    static class edge implements Comparable<edge>{
        int from,to,c,d,id;
        
        public edge(int x,int y,int u,int v,int z){
            from=x;
            to=y;
            c=u;
            d=v;
            id=z;
        }
        public int compareTo(edge o){
            return c-o.c;
        }
    }
 
    
    public static class s {
        static BufferedReader reader;
        static StringTokenizer tokenizer;
    
        /** call this method to initialize reader for InputStream */
        static void init(InputStream input) {
            reader = new BufferedReader(
                        new InputStreamReader(input) );
            tokenizer = new StringTokenizer("");
        }   
    
        /** get next word */
        static String ns() throws IOException {
            while ( ! tokenizer.hasMoreTokens() ) {
                //TODO add check for eof if necessary
                tokenizer = new StringTokenizer(
                    reader.readLine() );
            }
            return tokenizer.nextToken();
        }
    
        static int ni() throws IOException {
            return Integer.parseInt( ns() );
        }
    
        static double nd() throws IOException {
            return Double.parseDouble( ns() );
        }
        static long nl() throws IOException {
            return Long.parseLong( ns() );
        }
        
    }
}