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 i=0;i<q;i++){
            int n = in.nextInt();
            boolean valid = true;
            int minx =10000;
            int maxx = -10000;
            int miny = 10000;
            int maxy = -10000;
            int[] xn = new int[n];
            int[] yn = new int[n];
            for(int j=0;j<n;j++){
                int x = in.nextInt();
                int y = in.nextInt();
                xn[j] = x;
                yn[j] = y;
                if(x<minx){
                    minx=x;
                }
                if(x>maxx){
                    maxx=x;
                }
                if(y<miny){
                    miny=y;
                }
                if(y>maxy){
                    maxy=y;
                }
            }
            if(valid(xn,yn,minx,maxx,miny,maxy)){
                System.out.println("YES");
            }
            else{
                System.out.println("NO");
            }
        }
    }
    public static boolean valid(int[] xn,int[] yn,int minx,int maxx,int miny,int maxy){
        for(int i=0;i<xn.length;i++){
            if(xn[i]!=minx && 
               xn[i]!=maxx && 
               minx!=maxx && 
               yn[i]!=miny && 
                yn[i] !=maxy
              ){
                return false;
            }
        }
        return true;
    }
}