diff --git a/exercise/01/animal.cpp b/exercise/01/animal.cpp
new file mode 100644
index 0000000..2773405
--- /dev/null
+++ b/exercise/01/animal.cpp
@@ -0,0 +1,73 @@
+#include "animal.h"
+
+unsigned int insect::legs() const
+{
+	return 6;
+}
+
+std::wstring cockroach::species() const
+{
+	return L"cockroach";
+}
+
+unsigned int bird::legs() const
+{
+	return 2;
+}
+
+std::wstring sparrow::species() const
+{
+	return L"sparrow";
+}
+
+unsigned int spider::legs() const
+{
+	return 8;
+}
+
+std::wstring tarantula::species() const
+{
+	return L"tarantula";
+}
+
+std::wstring leg_counter::add_animal(const animal_factory& animal_fac)
+{
+	auto animal = animal_fac.get_animal();
+	nlegs += animal->legs();
+	return animal->species();
+}
+
+unsigned int leg_counter::legs() const
+{
+	return nlegs;
+}
+
+animal_factory::animal_factory(unsigned int id)
+{
+	switch (id)
+	{
+	case 1:
+		a = new cockroach;
+		break;
+	case 2:
+		a = new sparrow;
+		break;
+	case 3:
+		a = new tarantula;
+		break;
+	default:
+		throw std::invalid_argument("Wrong id.");
+	}
+}
+
+animal_factory::~animal_factory()
+{
+	if (!a)
+		return;
+	delete a;
+}
+
+animal* animal_factory::get_animal() const
+{
+	return a;
+}
diff --git a/exercise/01/animal.h b/exercise/01/animal.h
new file mode 100644
index 0000000..7c7a9ef
--- /dev/null
+++ b/exercise/01/animal.h
@@ -0,0 +1,64 @@
+#include <string>
+
+class animal
+{
+public:
+	virtual std::wstring species() const = 0;
+	virtual unsigned int legs() const = 0;
+	virtual ~animal() = default;
+};
+
+class animal_factory
+{
+	animal* a;
+public:
+	animal_factory(unsigned int id);
+	~animal_factory();
+	animal* get_animal() const;
+};
+
+
+class insect : public animal
+{
+public:
+	unsigned int legs() const override;
+};
+
+class cockroach : public insect
+{
+public:
+	std::wstring species() const override;
+};
+
+class bird : public animal
+{
+public:
+	unsigned int legs() const override;
+};
+
+class sparrow : public bird
+{
+public:
+	std::wstring species() const override;
+};
+
+class spider : public animal
+{
+public:
+	unsigned int legs() const override;
+};
+
+class tarantula : public spider
+{
+public:
+	std::wstring species() const override;
+};
+
+class leg_counter
+{
+	unsigned int nlegs;
+public:
+	leg_counter() : nlegs(0) {};
+	std::wstring add_animal(const animal_factory& animal_fac);
+	unsigned int legs() const;
+};