using System;

using System.Linq;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        var superStoneHatchet = new SuperStoneHatchet();

​

        foreach(var material in superStoneHatchet.GetAllMaterials())

            Console.WriteLine(material.Item.Name + ": " + material.Amount);

    }

    public abstract class Item

    {

        public abstract string Name { get; }

        public abstract string Description { get; }

        public abstract Ingredient[] Recipe { get; }

​

        private bool IsMaterial => Recipe == null || Recipe.Length == 0;

​

        public IEnumerable<Ingredient> GetAllMaterials()

        {

            return GetAllIngredients()

                .Where(ing => ing.Item.IsMaterial)

                .GroupBy(ing => ing.Item.Name)

                .Select(ing => new Ingredient(ing.First().Item, ing.Sum(i => i.Amount)));

        }

​

        private IEnumerable<Ingredient> GetAllIngredients()

        {

            if (Recipe != null)

            {

                foreach (Ingredient ing in Recipe)

                {

                    yield return ing;

​

                    foreach(var subIngredient in ing.Item.GetAllIngredients())

                        yield return new Ingredient(subIngredient.Item, ing.Amount * subIngredient.Amount);

                }

            }

        }

    }

​

​

    public struct Ingredient

    {

        public Item Item { get; }

        public int Amount { get; }

​

        public Ingredient(Item item, int amount)

        {

            Item = item;

            Amount = amount;

        }

​

        public IEnumerable<Ingredient> GetIngredientQuantities()

        {

            yield return this;

            foreach (var ing in Item.GetAllMaterials())

            {

                yield return new Ingredient(ing.Item, ing.Amount * this.Amount);

            }

        }

    }

    public class Wood : Item

    {

        public override string Name { get; }

        public override string Description { get; }

        public override Ingredient[] Recipe { get; }

​

        public Wood()

        {

            Name = "Wood";

            Description = "Type of resource.";

            Recipe = null;

        }

    }

​

    public class Stone : Item

    {

        public override string Name { get; }

        public override string Description { get; }

        public override Ingredient[] Recipe { get; }

​

        public Stone()

        {

            Name = "Stone";

            Description = "Type of resource.";

            Recipe = null;

        }

    }

    public class StoneHatchet : Item

    {

        public override string Name { get; }

        public override string Description { get; }

        public override Ingredient[] Recipe { get; }

​

        public StoneHatchet()

        {

            Name = "Stone Hatchet";

            Description = "Can be used as a weapon.";

            Recipe = new Ingredient[]

            {

                new Ingredient(new Wood(), 10),

                new Ingredient(new Stone(), 5)

            };

        }

    }

    public class SuperStoneHatchet : Item

    {

        public override string Name { get; }

        public override string Description { get; }

        public override Ingredient[] Recipe { get; }

​

        public SuperStoneHatchet()

        {

            Name = "Super Stone Hatchet";

            Description = "It’s like a stone hatchet, but with more stone.";

            Recipe = new Ingredient[]

            {

                new Ingredient(new StoneHatchet(), 2),

                new Ingredient(new Stone(), 5)

            };

        }

    }

}