import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {
    
   static boolean isDeg(int [][] list)
   {
      int minX = Integer.MAX_VALUE;
      int maxY = Integer.MIN_VALUE;
      int maxX = Integer.MIN_VALUE;
      int minY = Integer.MAX_VALUE;
      
      for (int [] point : list)
      {
         int x = point[0];
         int y = point[1];
         if (x < minX)
            minX = x;
         if (x > maxX)
            maxX = x;
         if (y < minY)
            minY = y;
         if (y > maxY)
            maxY = y;
      }
      
      for (int [] point : list)
      {
         int x = point[0];
         int y = point[1];
         boolean deg = (
                  (x >= minX && x <= maxX && (y == minY || y == maxY)) ||
                  (y >= minY && y <= maxY &&(x == minX || x == maxX) )
               );
         if (!deg)
         {
            return false;
         }
      }
      return true;
   }

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int queries = in.nextInt();
        for (int i=0; i<queries; i++){
            int points = in.nextInt();
            
            int [][] list = new int[points][2];
            for (int j=0; j<points; j++){
                int x = in.nextInt();
                int y = in.nextInt();
                list[j][0] = x;
                list[j][1] = y;
            }
            
            System.out.println(isDeg(list) ? "YES" : "NO");
        }
    }
}