How to add an extra level of sections with a LETTER headings below \subsubsection

Question

I well read different forums and the very good answer to the question "https://tex.stackexchange.com/questions/60209/how-to-add-an-extra-level-of-sections-with-headings-below-subsubsection/60212#60212?newreg=f4c391bc5752415792d4b68692c06e35". However, I didn't found any answer allowing me to use the method of @Gonzalo Medina (https://tex.stackexchange.com/a/60212/268708) while managing to change the number of the new "paragraph" section to a letter like "a".

In the example I would like that the "paragraph" \paragraph{Very very very funny part} section gives me "1.1.1.a Very very very funny part

Example:

\documentclass[11pt, A4paper]{article}

%Begin[section parameters]
\makeatletter
\renewcommand\paragraph{\@startsection{paragraph}{4}{\z@}%
            {-2.5ex\@plus -1ex \@minus -.25ex}%
            {1.25ex \@plus .25ex}%
            {\normalfont\normalsize\bfseries}}
\makeatother
\setcounter{secnumdepth}{4} % how many sectioning levels to assign numbers to
\setcounter{tocdepth}{4}    % how many sectioning levels to show in ToC
%End[section parameter]

\begin{document}
\maketitle

\tableofcontents

\section{Introduction} 
\subsection{Very funny part}
\subsubsection{Very Very funny part}
\paragraph{Very very very funny part}

\end{document}

Thank you for your answer

Answer 1

You just have to change the formatting of the counter by redefining \theparagraph. Btw. the option for DIN A4 paper is a4paper (in all lowercase).

\documentclass[11pt, a4paper]{article}

%Begin[section parameters]
\makeatletter
\renewcommand\paragraph{\@startsection{paragraph}{4}{\z@}%
            {-2.5ex\@plus -1ex \@minus -.25ex}%
            {1.25ex \@plus .25ex}%
            {\normalfont\normalsize\bfseries}}
\makeatother
\setcounter{secnumdepth}{4} % how many sectioning levels to assign numbers to
\setcounter{tocdepth}{4}    % how many sectioning levels to show in ToC
\renewcommand\theparagraph{\thesubsubsection.\alph{paragraph}}
%End[section parameter]

\begin{document}
%\maketitle

\tableofcontents

\section{Introduction} 
\subsection{Very funny part}
\subsubsection{Very Very funny part}
\paragraph{Very very very funny part}

\end{document}