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

public class Solution {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int t = sc.nextInt();
        while(t-->0){
            int n = sc.nextInt();
            if(n==1 || n==2)
                System.out.println("YES");
            else{
                int max_x = Integer.MIN_VALUE;
                int max_y = Integer.MIN_VALUE;
                int min_x = Integer.MAX_VALUE;
                int min_y = Integer.MAX_VALUE;
                
                int x[] = new int[n];
                int y[] = new int[n];
                for(int i=0;i<n;i++){
                    x[i] = sc.nextInt();
                    y[i] = sc.nextInt();
                    if(x[i]>max_x)
                        max_x = x[i];
                    if(x[i]<min_x)
                        min_x = x[i];
                    if(y[i]>max_y)
                        max_y= y[i];
                    if(y[i]<min_y)
                        min_y = y[i];
                }
            
                int flag=0,i;
                for(i=0;i<n && flag==0;i++){
                    if((x[i]==min_x || x[i]==max_x) && (y[i]==min_y || y[i]==max_y)){
                        
                }
                    else
                        flag=1;
                }
                if(flag==0 && i==n)
                    System.out.println("YES");
                else
                    System.out.println("NO");
            }
        }
    }
}