template<class T>
class IEnumerator
{
public:
	virtual bool MoveNext() = 0;
	virtual void Reset() = 0;
	virtual T Current() = 0;
	virtual ~IEnumerator() {}
};

template<class T>
class IEnumerable
{
public:
	virtual IEnumerator<T> GetEnumerator()
	{
		return (IEnumerator<T>)*this;
	}
};

template<class T>
class ICollection : public IEnumerable<T>
{
public:
	virtual int Count()
	{
		IEnumerator<T> e = GetEnumerator();
		e.Reset();
		int i = 0;
		while(e.MoveNext()) i++;
		return i + 1;
	}
	virtual bool IsReadOnly() = 0;
	virtual void Add(T item) = 0;
	virtual void Clear()
	{
		IEnumerator<T> e = GetEnumerator();
		e.Reset();
		do
		{
			Remove(e.Current());
		}
		while(e.MoveNext());
	}
	virtual bool Contains(T item)
	{
		IEnumerator<T> e = GetEnumerator();
		e.Reset();
		do
		{
			if(e.Current() == item)
				return true;
		}
		while (e.MoveNext());
		return false;
	}
	virtual void CopyTo(T *arr, int index, int count)
	{
		int i = 0;
		IEnumerator<T> e = GetEnumerator();
		e.Reset();
		do
		{
			arr[index + i++] = e.Current();
		}
		while (e.MoveNext() && i < count);
	}
	virtual bool Remove(T item) = 0;
};

template<class T>
class IComparer
{
public:
	virtual int Compare(T a, T b) = 0;
}