Leave plain text from HTML (Exercise)

using System;
using System.Collections.Generic;
using System.IO;
using System.Text.RegularExpressions;

namespace ConsoleTests
{
    class ConsoleTests
    {
        static void Main()
        {
            List<string> list = new List<string>();
            using (StreamReader reader = new StreamReader("file.txt"))
            {
                string line;
                while ((line = reader.ReadLine()) != null)
                {
                    list.Add(line);
                }
            }

            foreach (var stuff in list)
            {
                string temp = ExtractHtmlInnerText(stuff);
                if (temp.Length!=0)
                {
                    Console.WriteLine(temp);
                }
            }

        }
        public static string ExtractHtmlInnerText(string htmlText)
        {
            Regex regex = new Regex("(<.*?>\\s*)+", RegexOptions.Singleline);

            string resultText = regex.Replace(htmlText, " ").Trim();

            return resultText;
        }
    }
}