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

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        
        int q = in.nextInt();
        
        for(int j=0; j<q; j++){ 
            int n = in.nextInt();
            boolean success = true;
            int x2 = Integer.MIN_VALUE;
            int x1 = Integer.MAX_VALUE;
            int y2 = Integer.MIN_VALUE;
            int y1 = Integer.MAX_VALUE;
            int x[] = new int[n];
            int y[] = new int[n];
            
            for(int i=0; i<n; i++){                
                x[i] = in.nextInt();          
                y[i] = in.nextInt(); 
                if(x[i]>x2) x2=x[i];
                if(x[i]<x1) x1=x[i];
                if(y[i]>y2) y2=y[i];
                if(y[i]<y1) y1=y[i];
            }            
            
            for(int i=0; i<n; i++){               
                if(x1 != x[i] && x2 != x[i] && y1 != y[i] && y2 != y[i]) success = false;   
            }
            
            if(success) System.out.println("YES");
            else System.out.println("NO");
        }
    }
}