import java.io.*;
import java.util.*;

public class Solution {

    public static void main(String[] args) {
      Scanner scan = new Scanner(System.in);
      int q = scan.nextInt();
      for (int i = 0;i < q;i++) {
        int points = scan.nextInt();
        int[] pointsX = new int[points];
        int[] pointsY = new int[points];
        int maxX = -100000;
        int maxY = -100000;
        int minX = 100000;
        int minY = 100000;
        for (int j = 0;j < points;j++) {
          pointsX[j] = scan.nextInt();
          pointsY[j] = scan.nextInt();
          if(pointsX[j] > maxX)
            maxX = pointsX[j];
          if(pointsX[j] < minX)
            minX = pointsX[j];
          if(pointsY[j] > maxY)
            maxY = pointsY[j];
          if(pointsY[j] < minY)
            minY = pointsY[j];
        }
        //System.out.println("MaxX: " + maxX + " minX: " + minX + " maxY: " + maxY + " minY: " + minY);
        boolean allOn = true;
        for(int j = 0;j < points;j++) {
          if(!(pointsX[j] == maxX ||
             pointsX[j] == minX ||
             pointsY[j] == maxY ||
             pointsY[j] == minY)) {
            allOn = false;
          }   
        }
        System.out.println(allOn ? "YES" : "NO");
      }
      
    }
}