1class Material:
  2    _densities = {"Concrete": 2500, "Brick": 2000, "Stone": 1600, "Wood": 600, "Steel": 7700}
  3
  4    def __init__(self, mass):
  5        self.mass = mass
  6        self.used = False
  7
  8    def use(self):
  9        self.used = True
 10
 11    @property
 12    def density(self):
 13        return self.__class__.density
 14
 15    @property
 16    def volume(self):
 17        return float(self.mass / self.density)
 18    
 19class Concrete(Material):
 20    density = Material._densities["Concrete"]
 21    
 22class Brick(Material):
 23    density = Material._densities["Brick"]
 24
 25class Stone(Material):
 26    density = Material._densities["Stone"]
 27
 28class Wood(Material):
 29    density = Material._densities["Wood"]
 30
 31class Steel(Material):
 32    density = Material._densities["Steel"]
 33
 34class Alloy(Material):
 35    density = None
 36    _base_materials = []
 37
 38    @classmethod
 39    def calculate_density(cls):
 40        if not cls._base_materials:
 41            return None
 42        return sum(Material._densities[material] for material in cls._base_materials) / len(cls._base_materials)
 43
 44class Factory:
 45    _material_classes = {"Concrete": Concrete, "Brick": Brick, "Stone": Stone, "Wood": Wood, "Steel": Steel}
 46    all_factories_available_materials = []
 47
 48    def __init__(self):
 49        self.__available_materials = []
 50
 51    def __call__(self, *args, **kwargs):
 52        if (args and kwargs) or (not args and not kwargs):
 53            raise ValueError("Invalid arguments")
 54        if kwargs:
 55            return self.__create_materials(**kwargs)
 56        elif args:
 57            return self.__create_alloy(*args)
 58        
 59    def __create_materials(self, **kwargs):
 60        current_materials = []
 61        for name, mass in kwargs.items():
 62            if name in self._material_classes:
 63                material_type = self._material_classes[name]
 64            else:
 65                raise ValueError("Invalid argument name")
 66            material = material_type(mass)
 67            current_materials.append(material)
 68            self.__available_materials.append(material)
 69            self.all_factories_available_materials.append(material)
 70        return tuple(current_materials)
 71    
 72    def __create_alloy(self, *args):
 73        for material in args:
 74            if material.used:
 75                raise AssertionError("Material already used")
 76            else:
 77                material.use()
 78
 79        alloy_name = "_".join(sorted(material for name in args for material in name.__class__.__name__.split("_")))
 80        sum_mass = sum(material.mass for material in args)
 81        if alloy_name in self._material_classes:
 82            alloy_class = self._material_classes[alloy_name]
 83        else:
 84            base_materials = [material for material in alloy_name.split("_")]
 85            avg_density = sum(Material._densities[material] for material in base_materials) / len(base_materials)
 86            alloy_class = type(alloy_name, (Alloy,), {"_base_materials": base_materials, "density": avg_density})
 87            self._material_classes[alloy_name] = alloy_class
 88        instance = alloy_class(sum_mass)
 89        self.__available_materials.append(instance)
 90        self.all_factories_available_materials.append(instance)
 91        return instance
 92    
 93    def can_build(self, volume):
 94        avaible_volume = sum(material.volume for material in self.__available_materials if not material.used)
 95        return avaible_volume >= volume
 96    
 97    @classmethod
 98    def can_build_together(cls, volume):
 99        avaible_volume = sum(material.volume for material in cls.all_factories_available_materials if not material.used)
100        return avaible_volume >= volume