BuildingsIterator.Filters.ChinFilterByAlphabetCardinality.GetAlphabetPowerFromBuilding C# (CSharp) Метод

        private int GetAlphabetPowerFromBuilding(string building)
        {
            var chars = new List<char>();
            foreach (char t in building)
            {
                if (!chars.Contains(t))
                {
                    chars.Add(t);
                }
            }

            return chars.Count;
        }