Word Count

/* Write a program that reads a list of words from the file words.txt and finds how many times each of the words is contained in another file text.txt. Matching should be case-insensitive.
 * Write the results in file results.txt. Sort the words by frequency in descending order. Use StreamReader in combination with StreamWriter. */

namespace _03.Word_Count
{
    using System.Collections.Generic;
    using System.IO;
    using System.Linq;
    using System.Text;
    using System.Text.RegularExpressions;

    class WordCount
    {
        const string Pattern = @"\b[\w']+\b";

        static void Main(string[] args)
        {
            string words = string.Empty;
            var reader = new StreamReader("../../words.txt");
            using (reader)
            {
                words = reader.ReadToEnd();
            }

            string text = string.Empty;
            using (reader = new StreamReader("../../text.txt"))
            {
                text = reader.ReadToEnd();
            }

            Dictionary<string, int> wordsCount = new Dictionary<string, int>();
            MatchCollection matches1 = Regex.Matches(words, Pattern);
            MatchCollection matches2 = Regex.Matches(text, Pattern);
            foreach (Match word in matches1)
            {
                foreach (Match match in matches2)
                {
                    if (word.ToString().ToLower() == match.ToString().ToLower())
                    {
                        if (!wordsCount.ContainsKey(word.ToString()))
                        {
                            wordsCount[word.ToString()] = 0;
                        }

                        wordsCount[word.ToString()]++;
                    }
                }
            }

            List<KeyValuePair<string, int>> keyValuePairs = wordsCount
                .OrderByDescending(p => p.Value).ToList();

            using (var stream = new FileStream("../../result.txt", FileMode.Create))
            {
                using (var writer = new StreamWriter(stream, Encoding.ASCII, 4096))
                {
                    foreach (var pair in keyValuePairs)
                    {
                        writer.WriteLine("{0} - {1}", pair.Key, pair.Value);
                    }
                }
            }
        }
    }
}