HackerRankTweets

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;
            int occurences = 0;
            List<int> numbers = new List<int>();
            string pattern = @"(hackerrank)";
            Regex regex = new Regex(pattern);
            List<string> output = new List<string>();
            do
            {
                string input = Console.ReadLine();
                input = input.ToLower();
                if (regex.IsMatch(input) == true)
                {
                    occurences++;
                }
                counter++;
            } while (counter < n);
            Console.WriteLine(occurences);
        }
    }
}