Latex Beamer first Page white with Item Alert

Question

The following Beamer presentation first shows a fully white page. How can the first white page be removed so the first page has only the first topmost item?

\documentclass{beamer}
\begin{document}
  \begin{frame}[t]
  \frametitle{Test}
  \begin{itemize}[<+(1)-| alert@+(1)>]
    \item item 1
    \item item 2
    \begin{itemize}
      \item<alert@2-> subitem 1
      \item<alert@2-> subitem 2
    \end{itemize}
    \item item 3
    \item item 4
    \item item 5
    \item item 6
  \end{itemize}
  \end{frame}
\end{document}

Answer 1

The (1) in +(1)- will increase the overlay by 1. If you want to start immediately, remove the (1)

\documentclass{beamer}
\begin{document}
  \begin{frame}[t]
  \frametitle{Test}
  \begin{itemize}[<+-| alert@+>]
    \item item 1
    \item item 2
    \begin{itemize}
      \item<alert@2> subitem 1
      \item<alert@2> subitem 2
    \end{itemize}
    \item item 3
    \item item 4
    \item item 5
    \item item 6
  \end{itemize}
  \end{frame}
\end{document}