Saying Hy

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Text.RegularExpressions;
namespace ConsoleApplication6
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int counter = 0;
            List<string> validOrNot = new List<string>();
            string pattern = @"^([hi]+\s)(?![D|d]).+";
            Regex regex = new Regex(pattern);
            do
            {
                string input = Console.ReadLine();
                string check = input.ToLower();
                if (regex.IsMatch(check) == true)
                {
                    validOrNot.Add(input);
                }
                counter++;
            } while (counter < n);
            foreach (var status in validOrNot)
            {
                Console.WriteLine(status);
            }
        }
    }
}