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 sc  = new Scanner(System.in);
        int q = sc.nextInt();
        for(int t = 0;t < q;t++){
            int n = sc.nextInt();
            int i,j,k;
            int x[] = new int[n];
            int y[] = new int[n];
            int xx = -100000, yy = -100000, xxx = 100000, yyy = 100000;
            for(i = 0;i < n;i++){
                x[i] = sc.nextInt();
                y[i] = sc.nextInt();
                if(x[i] > xx){
                    xx = x[i];
                }
                if(x[i] < xxx){
                    xxx = x[i];
                }
                if(y[i] < yyy){
                    yyy = y[i];
                }
                if(y[i] > yy){
                    yy  = y[i];
                }
            }
            int flag = 0;
            for(i = 0;i < n;i++){
                if((x[i] == xx || x[i] == xxx) || (y[i] == yy || y[i] == yyy)){
                    
                }
                else{
                    flag = 1;
                }
            }
            
            if(flag == 1){
                System.out.println("NO");
            }
            else{
                System.out.println("YES");
            }
        }
        
        
    }
}