Linq, dictionary, regular expresions

using System;
using System.Collections.Generic;
using System.IO;
using System.Text.RegularExpressions;
using System.Security;
using System.Linq;
//Write a program that reads a list of words from a file words.txt and finds how many times each of
//the words is contained in another file test.txt. The result should be written in the file
//result.txt and the words should be sorted by the number of their occurrences in descending order.
//Handle all possible exceptions in your methods.
class RemoveWords
{
    static void Main()
    {
        try
        {
            Dictionary<string, int> words = new Dictionary<string, int>();
            using (StreamReader reader = new StreamReader("words.txt"))
            {
                ReadWords(reader, words);
            }
            using (StreamReader reader = new StreamReader("test.txt"))
            using (StreamWriter writer = new StreamWriter("result.txt"))
            {
                CountMatches(reader, words);
                WriteWords(words, writer);
            }
        }
        catch (FileNotFoundException err)
        {
            Console.WriteLine(err.Message);
        }
        catch (DirectoryNotFoundException err)
        {
            Console.WriteLine(err.Message);
        }
        catch (IOException err)
        {
            Console.WriteLine(err.Message);
        }
        catch (UnauthorizedAccessException err)
        {
            Console.WriteLine(err.Message);
        }
        catch (ArgumentNullException err)
        {
            Console.WriteLine(err.Message);
        }
        catch (ArgumentException err)
        {
            Console.WriteLine(err.Message);
        }
        catch (OutOfMemoryException err)
        {
            Console.WriteLine(err.Message);
        }
        catch (NotSupportedException err)
        {
            Console.WriteLine(err.Message);
        }
        catch (SecurityException err)
        {
            Console.WriteLine(err.Message);
        }
        catch (RegexMatchTimeoutException err)
        {
            Console.WriteLine(err.Message);
        }
    }

    private static void WriteWords(Dictionary<string, int> words, StreamWriter writer)
    {
        var sortedWords = (from entry in words orderby entry.Value descending select entry).ToDictionary(pair => pair.Key, pair => pair.Value);
        foreach (var item in sortedWords)
        {
            writer.WriteLine(item.Key + " " + item.Value);
        }
    }

    private static void CountMatches(StreamReader reader, Dictionary<string, int> words)
    {
        List<string> keys = new List<string>(words.Keys);
        string line;

        while ((line = reader.ReadLine()) != null)
        {
            foreach (string key in keys)
            {
                words[key] += Regex.Matches(line, "\\b" + key + "\\b").Count;
            }
        }
    }

    private static void ReadWords(StreamReader reader, Dictionary<string, int> words)
    {
        string line;
        while ((line = reader.ReadLine()) != null)
        {
            string[] word = line.Split();
            foreach (string item in word)
            {
                words.Add(item, 0);
            }
        }
    }
}