import java.io.*;
import java.util.*;
class DegRec {
    public static void main(String[] args) throws IOException{
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        int t = Integer.parseInt(in.readLine());
        while(t-->0){
            int n = Integer.parseInt(in.readLine());
            int[][] a = new int[n][2];
            boolean flag = true;
            int xmin=Integer.MAX_VALUE,xmax=Integer.MIN_VALUE,ymin=Integer.MAX_VALUE,ymax=Integer.MIN_VALUE;
            for(int i=0;i<n;i++){
                String[] input = in.readLine().split("\\s+");
                a[i][0]=Integer.parseInt(input[0]);
                a[i][1]=Integer.parseInt(input[1]);
                xmin = (xmin>a[i][0])?a[i][0]:xmin;
                xmax = (xmax<a[i][0])?a[i][0]:xmax;
                ymin = (ymin>a[i][1])?a[i][1]:ymin;
                ymax = (ymax<a[i][1])?a[i][1]:ymax;
            }
            for(int i=0;i<n;i++){
                int x = a[i][0],y=a[i][1];
                if(x<xmin || x>xmax || y<ymin || y>ymax){
                    flag=false;
                    break;
                }
                if(y>ymin && y<ymax && (x!=xmin && x!=xmax)){
                    flag = false;
                    break;
                }
                if(x>xmin && x<xmax && (y!=ymin && y!=ymax)){
                    flag = false;
                    break;
                }
            }
            System.out.println((flag)?"YES":"NO");
        }
    }
}