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

public class Solution {
    
    public static boolean is_rectangle(int[] x, int[] y,int length){
        if(length==1){
            return false;
        }
        int[] _x = x.clone();
        int[] _y = y.clone();
        Arrays.sort(_x);
        Arrays.sort(_y);
        for(int i=0;i<length;i++){
            if(!(x[i]== _x[0] || x[i]==_x[length-1] || y[i]== _y[0] || y[i]==_y[length-1])){
                return false;
                
            }
        }
        return true;
    }
    
    
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int query_num = in.nextInt();
        for(int k=0;k<query_num;k++){
            int point_num = in.nextInt();
            int[] x = new int[point_num];
            int[] y = new int[point_num];
            for(int j=0;j<point_num;j++){
                x[j] = in.nextInt();
                y[j] = in.nextInt();
            }               
            boolean rectangle = is_rectangle(x,y,point_num);
            System.out.println(rectangle?"YES":"NO");
        }
        in.close();
    }
}