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

public class Solution {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int q = sc.nextInt();
        for (int qq = 0; qq < q; qq++) {
            int n = sc.nextInt();
            ArrayList<Integer> a = new ArrayList<Integer>();
            ArrayList<Integer> b = new ArrayList<Integer>();
            for (int i = 0; i < n; i++) {
                int x = sc.nextInt();
                a.add(x);
                int y = sc.nextInt();
                b.add(y);
            }
            ArrayList<Integer> aa =(ArrayList<Integer>) a.clone();
            ArrayList<Integer> bb =(ArrayList<Integer>) b.clone();
            Collections.sort(a);
            Collections.sort(b);
            int xmin = a.get(0), xmax = a.get(a.size() -1 );
            int ymin = b.get(0), ymax = b.get(b.size() -1 );
            boolean res = true;
            for (int i = 0, leng = a.size() ; i < leng; i++) {
                if (aa.get(i) != xmin && aa.get(i) != xmax && bb.get(i) != ymin && bb.get(i) != ymax)
                    res = false;
            }
            if (res) System.out.println("YES");
            else
                System.out.println("NO");
        }
    }
}