Change LaTex itemizations formats

Inspired by the way my professor formats their LaTeX assignments.

Input

\documentclass{minimal}

\begin{document}

\begin{itemize}

\item[1.] Item 1
\subitem a
\subitem b
\subitem c
\item[2.] Item 2
\subitem a
\subitem b
\item[3.] Item 3
\subitem b
\subitem c
\item[4.] Item 4
\subitem b
\subitem c
\item[5.] Item 5
\subitem b
\subitem c

\end{itemize}

\end{document}

Output

\documentclass{minimal}

\begin{document}

\begin{enumerate}

\item Item 1
\begin{enumerate}
	\item a
	\item b
	\item c
\end{enumerate}
\item Item 2
\begin{enumerate}
	\item a
	\item b
\end{enumerate}
\item Item 3
\begin{enumerate}
	\item b
	\item c
\end{enumerate}
\item Item 4
\begin{enumerate}
	\item b
	\item c
\end{enumerate}
\item Item 5
\begin{enumerate}
	\item b
	\item c
\end{enumerate}

\end{enumerate}

\end{document}