namespace stepik
{
template <typename T>
  class shared_ptr
  {
  public:
    shared_ptr(T *other = 0)
    {
        ptr = other;
        if (ptr) link = new long(1);
        else link = nullptr;

    }

    ~shared_ptr()
    {
      decrease();
    }

    shared_ptr(const shared_ptr & other):ptr(other.ptr)
    {
        link = other.link;
        if (link) *link += 1;
    }

    shared_ptr& operator=(const shared_ptr & other)
    {
         if (this!=&other)
        {
            decrease();
            ptr  =  other.ptr;
            link = other.link;
            if (link) ++(*link);

        }
        return *this;
    }

    explicit operator bool() const
    {
        return (ptr!=nullptr);
    }

    T* get() const
    {
        return ptr;
    }

    long use_count() const
    {
        if (link)
        return *link;
        else
        return 0;
    }

    T& operator*() const
    {
        return *ptr;
    }

    T* operator->() const
    {
        return ptr;
    }

    void swap(shared_ptr& x) noexcept
    {
         std::swap(ptr, x.ptr);
         std::swap(link, x.link);
    }

    void reset(T *otherptr = 0)
    {
        decrease();
        ptr  = nullptr;
        link = nullptr;
        ptr = otherptr;
        if (ptr) link = new long (1);
        else link=nullptr;
    }

  private:
      T *ptr;
      long* link;
      void decrease ()
      {
          if (ptr && link && !(--(*link))){
             delete ptr;
             delete link;
             link = 0;
          }
      }
  };
} // namespace stepik