using System;
using System.Collections.Generic;
using System.IO;
class Solution {
    static void Main(String[] args) {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution */
        int q = Convert.ToInt32(Console.ReadLine());
        
        for(int i = 0; i < q;i++)
        {
            int n = Convert.ToInt32(Console.ReadLine());
            bool result = true;
            for(int j = 0; j < n;j++)
            {
                int[] coord = Array.ConvertAll(Console.ReadLine().Split(' '),Int32.Parse);
                int x = coord[0], y = coord[1];
                
                result = result && (x == 0 || y== 0);
            }
            Console.WriteLine(result? "YES" : "NO");
        }
        
    }
}