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

public class Solution {

    public static void main(String[] args) {
        Scanner in=new Scanner(System.in);
        int a[]=new int[10001];
        int b[]=new int[10001];

        int q=in.nextInt();
        while(q-->0)
            {
            int n=in.nextInt();
            int x[]=new int[n];
                        int y[]=new int[n];
            if(n<=2)
                {
                System.out.println("YES");
            }else{
 int count=0;
            for(int i=0;i<n;i++)
                {
                x[i]=in.nextInt();
                y[i]=in.nextInt();
                a[Math.abs(x[i])]++;
                b[Math.abs(y[i])]++;
               
                
            }
                Arrays.sort(x);
                Arrays.sort(y);
                
                if((a[x[0]]+a[x[n-1]]+b[y[0]]+b[y[n-1]])/2==n)
                    System.out.println("YES");
                else
                    System.out.println("NO");
               
                
           
            }
        }
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
    }
}