#include <vector>
#include <type_traits>

template <
	std::size_t levels,
	template<typename _> typename Wrapper_t,
	typename T
>
struct nest
{
	using type = Wrapper_t<typename nest<levels - 1, Wrapper_t, T>::type>;
};

template <template<typename _> typename Wrapper_t, typename T>
struct nest<0, Wrapper_t, T>
{
	using type = Wrapper_t<T>;
};

template <
	std::size_t levels,
	template<typename _> typename Wrapper_t,
	typename T
>
using nest_t = typename nest<levels, Wrapper_t, T>::type;

template <typename T>
using default_allocator_vector = std::vector<T>;