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

public class Solution {

    public static void main(String[] args) {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
        Scanner sc = new Scanner(System.in);
        int q=sc.nextInt();
        for(int i=0;i<q;i++){
            int n=sc.nextInt();
            int a[][]=new int[n][2];
            int minx=Integer.MAX_VALUE,miny=Integer.MAX_VALUE,maxx=Integer.MIN_VALUE,maxy=Integer.MIN_VALUE;
            int j=0;
            for(j=0;j<n;j++){
                a[j][0]=sc.nextInt();
                a[j][1]=sc.nextInt();
                if(minx>a[j][0])
                    minx=a[j][0];
                if(maxx<a[j][0])
                    maxx=a[j][0];
                if(miny>a[j][1])
                    miny=a[j][1];
                if(maxy<a[j][1])
                    maxy=a[j][1];
            }
            for(j=0;j<n;j++){
                if(((a[j][0]==minx || a[j][0]==maxx) && a[j][1]>=miny && a[j][1]<=maxy) 
                   || ((a[j][1]==miny || a[j][1]==maxy) && a[j][0]>=minx && a[j][0]<=maxx))
                    continue;
                else
                    break;
            }
            if(j==n)
                System.out.println("YES");
            else
                System.out.println("NO");
        }
    }
}