private static List<string> wordList;
private static List<string> curseWords;
private static int currentWordIndex;
private static Dictionary<string, int> wordCountDict;
private static readonly object wordCountCalculatorSyncObj = new object();

public static void CalculateWordCounts() {
	wordList = GetWordList();
	curseWords = GetCurseWords();
	currentWordIndex = 0;
	wordCountDict = new Dictionary<string, int>();

	Thread threadA = new Thread(ThreadDoWork);
	Thread threadB = new Thread(ThreadDoWork);
	Thread threadC = new Thread(ThreadDoWork);
	Thread threadD = new Thread(ThreadDoWork);
	threadA.Start();
	threadB.Start();
	threadC.Start();
	threadD.Start();
	threadA.Join();
	threadB.Join();
	threadC.Join();
	threadD.Join();
}

private static void ThreadDoWork() {
	bool atLeastOneWordRemaining;
	int thisWordIndex;
	lock (wordCountCalculatorSyncObj) {
		thisWordIndex = currentWordIndex;
		currentWordIndex = currentWordIndex + 1;
	}
	if (thisWordIndex >= wordList.Count) atLeastOneWordRemaining = false;
	else atLeastOneWordRemaining = true;

	while (atLeastOneWordRemaining) {
		string thisWord = wordList[thisWordIndex]
			.ToUpper()
			.Replace("-", String.Empty)
			.Replace("'", String.Empty)
			.Trim();

		if (curseWords.Contains(thisWord)) Console.WriteLine("Curse word detected!");

		lock (wordCountCalculatorSyncObj) {
			bool firstOccurrenceOfWord = !wordCountDict.ContainsKey(thisWord);
		
			if (firstOccurrenceOfWord) wordCountDict.Add(thisWord, 1);
			else wordCountDict[thisWord] = wordCountDict[thisWord] + 1;
			thisWordIndex = currentWordIndex;
			currentWordIndex = currentWordIndex + 1;
		}
		if (thisWordIndex >= wordList.Count) atLeastOneWordRemaining = false;
	}
}