import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int q = in.nextInt();
        int x,y,n,x1,y1;
        boolean flag  = true;
        for( ; q>0 ; q--) {
            x=0;
            y=0;
            x1=0;
            y1=0;
            n = in.nextInt();
            flag  = true;
            int a[][] = new int[n][2];
            int i=0;
            for(i=0 ; i<n ; i++) {
                a[i][0] = in.nextInt();
                a[i][1] = in.nextInt();
                x = Math.max(x,a[i][0]);
                y = Math.max(y,a[i][1]);
                x1 = Math.min(x1,a[i][0]);
                y1 = Math.min(y1,a[i][0]);
            }
            int mid_x = (x+Math.abs(x1))/2;
            int mid_y = (y+Math.abs(y1))/2;
            if((x!=y) && (x1!=y1)) {
                i=n;
                flag = false;
            }
            else {
                i=0;
            }
           for( ; i<n ; i++) {
                if(a[i][0]>x || a[i][1]>y) {
                   
                    flag = false;
                    break;
                }
              else if(a[i][0]<x1 || a[i][1]<y1) {
                  
                   flag  = false;
                   break;
               }
              else if(a[i][0]==a[i][1]) {
                   if(a[i][0]!=x1) {
                       if(a[i][0]!=x) {
                           if(a[i][0]==mid_x || a[i][1]==mid_y) {
                               if(a[i][0]!=0 || a[i][1]!=0) {
                               
                       flag = false;
                       break;
                               }
                           }
                       }
                   }
               }
               
               else {
                   if((a[i][0]!=0) && (a[i][1]!=0)) {
                       
                       flag  = false;
                       break;
                   }
               }
               
            }
            if(flag) {
                System.out.println("YES");
            }
            else {
                System.out.println("NO");
            }
           
        }
    }
}