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();
        for(int q=0;q<Q;q++){
            int N=in.nextInt();
            int mv=100000;
            int Xmax=-mv;
            int Xmin=mv;
            int Ymax=-mv;
            int Ymin=mv;
            int[] X=new int[N];
            int[] Y=new int[N];
            boolean b=true;
            for(int i=0;i<N;i++){
                X[i]=in.nextInt();
                Y[i]=in.nextInt();
                Xmin=(Xmin>X[i])?X[i]:Xmin;
                Xmax=(Xmax<X[i])?X[i]:Xmax;
                Ymin=(Ymin>Y[i])?Y[i]:Ymin;
                Ymax=(Ymax<Y[i])?Y[i]:Ymax;
            }
            for(int i=0;i<N &&b ;i++){
                if(X[i]!=Xmin && X[i]!=Xmax && Y[i]!=Ymin && Y[i]!=Ymax){
                    b=false;
                }
            }
            System.out.println(b?"YES":"NO");
        }
    }
}