juol

    using System;
    using System.Text;

    namespace Goal
    {
        class Program
        {
            static void Main(string[] args)
            {
                Console.WriteLine(G("al"));
                Console.WriteLine(G()("al"));
                Console.WriteLine(G()()()()()("al"));
            }

            static StringBuilder accumulator = new StringBuilder();
            delegate dynamic GoalDelegate(string s = "o");

            static dynamic G(string s = "o")
            {
                switch (s)
                {
                    case "o":
                        accumulator.Append("o");
                        return (GoalDelegate)G;
                    case "al":
                        string result = "G" + accumulator.ToString() + "al";
                        accumulator.Clear();
                        return result;
                    default:
                        return null;
                }
            }
        }

    }