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) throws Exception {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
        BufferedReader br = new BufferedReader(new InputStreamReader (System.in));
        int q= Integer.parseInt(br.readLine());
        String ans;
        while(q>0)
            {
            int n = Integer.parseInt(br.readLine());
            int [][] p = new int [n][2];
            
                String [] data = br.readLine().split(" ");
                p[0][0] = Integer.parseInt(data[0]);
                p[0][1] = Integer.parseInt(data[1]);
                int minx = p[0][0];
            int miny = p[0][1];
            int maxx = minx;
            int maxy = miny;
            for(int i=1;i<n;i++)
                {
                String [] dat = br.readLine().split(" ");
                p[i][0] = Integer.parseInt(dat[0]);
                p[i][1] = Integer.parseInt(dat[1]);
                
                if(minx>p[i][0])
                    minx=p[i][0];
                if(maxx<p[i][0])
                    maxx=p[i][0];
                if(miny>p[i][1])
                    miny = p[i][1];
                if(maxy<p[i][1])
                    maxy = p[i][1];
                
                
            }
            ans = "YES";
            int i=0;
            for(;i<n;i++)
                {
                if((p[i][0] == minx || p[i][0] == maxx)||(p[i][1] == miny || p[i][1] == maxy)){
                    continue;
                    
                }
                else
                    {
                    ans="NO";
                    break;
                }
                    
            }
       
            System.out.println(ans);
            
            q--;
            
        }
    }
}