/// \brief Returns the winner team.
/// \param[in] min_owned_items Minimum number of items the winner team must have.
/// \return Winner team or 0 if 2 or more teams own items or -1 if no team own any items.
/// \brief Returns the winner team.
/// \param[in] min_owned_items Minimum number of items the winner team must have.
/// \return Winner team or 0 if 2 or more teams own items or -1 if no team own any items.