import java.util.Scanner;
import java.util.*;

public class Solution {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int q = sc.nextInt();
        while(q-->0){
            int n = sc.nextInt();
            HashMap<Integer, Integer> map = new HashMap<Integer, Integer>();
            int xmin=Integer.MAX_VALUE;
            int xmax=Integer.MIN_VALUE;
            int ymin=Integer.MAX_VALUE;
            int ymax=Integer.MIN_VALUE;
            for(int i=0; i<n; i++){
                int x = sc.nextInt();
                int y = sc.nextInt();
                map.put(x,y);
                if(xmin>x)
                    xmin = x;
                if(xmax<=x)
                    xmax=x;
                if(ymin>y)
                    ymin=y;
                if(ymax<=y)
                    ymax=y;
            }
            Iterator entries = map.entrySet().iterator();
            int flag=0;
            while (entries.hasNext()) {
                Map.Entry entry = (Map.Entry) entries.next();
                Integer x = (Integer)entry.getKey();
                Integer y = (Integer)entry.getValue();
                if(x==xmin||x==xmax||y==ymin||y==ymax)
                    continue;
                else
                    flag=1;
                break;
            }
            if(flag==0)System.out.println("YES");
            else System.out.println("NO");
        }
    }
}