namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {
           ExtendedDictionary<int> dic = new ExtendedDictionary<int>();
            dic.Insert(1, "lala");
            dic.Insert(2, "dydy");
            int zm = dic.Suum();
            Console.WriteLine(zm);
        }
    }

    public class ExtendedDictionary<T> where T :
    {
        private Dictionary<T, string> items;
        private int sum ;
       // public int Sum{  get { return sum;} }
       // public int Sum{ get; set;}

        public ExtendedDictionary()
        {
            items = new Dictionary<T, string>();
        }

        public void Insert(T key, string valuee)
        {
            items.Add(key, valuee );
        }

        public void Delete(T key)
        {
            items.Remove(key);
        }

        public int Suum()
        {
            return items.Sum(e => e.Value.Length);
        }
    }
}