How to Exclude Total Slide Number from Beamer Slide

Question

Here is a MWE for my Beamer slides:

\documentclass[compress]{beamer}

\usetheme{Madrid}
\usecolortheme{seagull}

\setbeamertemplate{navigation symbols}{}

\title[Name of Presentation Slides]{Name}
\author[Author A and Author B]{Author A and Author B}
\date[September 20, 2017]{September 20, 2017}

\begin{document}

\begin{frame}
\frametitle{First Slide}
\textbf{Letters}
\begin{itemize}
    \item A
    \item B
    \item C
\end{itemize}

\end{frame}

\end{document}

I would like to keep the same format in the bottom bar, but simply exclude the slide total, so that only the current slide is displayed.

I tried the following solutions from these questions (Beamer : Page number without total number of pages and Beamer frame number without total, but they never quite worked right, always modifying the other parts of the bottom bar in some way.

1.

\setbeamertemplate{footline}
    {\begin{beamercolorbox}[sep=1ex]{author in head/foot}
      \rlap{\textit{\insertshorttitle}}\hfill\insertauthor\hfill\llap{\insertframenumber}%
      \end{beamercolorbox}%
}

2.

\setbeamertemplate {footline}{\quad\hfill\insertframenumber\strut\quad}

3.

\setbeamertemplate{footline}{% 
  \hfill% 
  \usebeamercolor[fg]{page number in head/foot}% 
  \usebeamerfont{page number in head/foot}% 
  \insertframenumber%
  %\,/\,\inserttotalframenumber
  \kern1em\vskip2pt% 
}

What is to be done in my instance?

Answer 1

The Madrid theme uses the footline from the infolines outer theme, you can redefine it like this:

\documentclass[compress]{beamer}

\usetheme{Madrid}
\usecolortheme{seagull}

\setbeamertemplate{navigation symbols}{}

\title[Name of Presentation Slides]{Name}
\author[Author A and Author B]{Author A and Author B}
\date[September 20, 2017]{September 20, 2017}

\makeatletter
\setbeamertemplate{footline}{
  \leavevmode%
  \hbox{%
  \begin{beamercolorbox}[wd=.333333\paperwidth,ht=2.25ex,dp=1ex,center]{author in head/foot}%
    \usebeamerfont{author in head/foot}\insertshortauthor\expandafter\ifblank\expandafter{\beamer@shortinstitute}{}{~~(\insertshortinstitute)}
  \end{beamercolorbox}%
  \begin{beamercolorbox}[wd=.333333\paperwidth,ht=2.25ex,dp=1ex,center]{title in head/foot}%
    \usebeamerfont{title in head/foot}\insertshorttitle
  \end{beamercolorbox}%
  \begin{beamercolorbox}[wd=.333333\paperwidth,ht=2.25ex,dp=1ex,right]{date in head/foot}%
    \usebeamerfont{date in head/foot}\insertshortdate{}\hspace*{2em}
    \insertframenumber{}%
%     / \inserttotalframenumber
    \hspace*{2ex} 
  \end{beamercolorbox}}%
  \vskip0pt%
}
\makeatother

\begin{document}

\begin{frame}
\frametitle{First Slide}
\textbf{Letters}
\begin{itemize}
    \item A
    \item B
    \item C
\end{itemize}

\end{frame}

\end{document}

---

Starting with beamer v. 3.49 the new beamer template page number in head/foot simplifies this to:

\documentclass[compress]{beamer}

\usetheme{Madrid}
\setbeamertemplate{page number in head/foot}[framenumber]

\begin{document}

\begin{frame}
\end{frame}

\end{document}