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

public class Solution {

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int a = scan.nextInt();
        for(int i = 0; i < a; i++){
            int b = scan.nextInt();
            int[][] c = new int[b][2];
            int xmin = 10000;
            int ymin = 10000;
            int xmax = -10000;
            int ymax = -10000;
            for(int j = 0; j < b; j++){
                c[j][0] = scan.nextInt();
                xmin = Math.min(xmin, c[j][0]);
                xmax = Math.max(xmax, c[j][0]);
                c[j][1] = scan.nextInt();
                ymin = Math.min(ymin, c[j][1]);
                ymax = Math.max(ymax, c[j][1]);
            }
            String check = "YES";
            for(int[] d : c){
                if(d[0] != xmin && d[0] != xmax && d[1] != ymin && d[1] != ymax){
                    check = "NO";
                }
            }
            System.out.println(check);
            
        }
    }
}