MBGen.WordList.GetMultiClassList C# (CSharp) Method

        private List<int> GetMultiClassList(params string[] classNames)
        {
            List<int> words = new List<int>();
            List<int> firstClass = this.Classes[classNames[0]];
            for (int i = 0; i < firstClass.Count; i++) // loop through every item of the first class
            {
                int matchCount = 0;
                for (int j = 1; j < classNames.Length; j++) // loop through all the other classes
                {
                    List<int> currentClass = this.Classes[classNames[j]];
                    for (int k = 0; k < currentClass.Count; k++) // search their contents and match them up
                    {
                        if (firstClass[i] == currentClass[k])
                        {
                            matchCount++;
                        }
                    }
                }
                if (matchCount == classNames.Length - 1)
                {
                    words.Add(firstClass[i]);
                }
            }
            return words;
        }