This question continues my [another](https://tex.stackexchange.com/questions/423545/tikz-how-to-automatically-draw-a-rectangle-in-a-rectangle).

My code:

```
\documentclass{scrartcl}
\usepackage{tikz}
\usetikzlibrary{positioning}

\tikzset{
         signal/.style = coordinate,
         sum/.style = {
                       draw,
                       circle,
                       inner sep = 0pt,
                       minimum size = 2mm
                      }
        }

\begin{document}

  \begin{tikzpicture}[auto]

    %placing the nodes
    \node[signal] (input x) {};
    \node[
          sum,
          right = of input x
         ] (sum) {};
    \node[
          signal,
          above=of sum
         ] (input y) {};
    \node[
          signal,
          right=of sum
         ] (output) {};

    %connecting the nodes
    \draw
      [->] (input x) -- node {$x$} (sum);
    \draw
      [->] (input y) -- node {$y$} node[pos = .95] {$-$} (sum);
    \draw
    [->] (sum)       -- node {$z$} (output);

  \end{tikzpicture}

\end{document}

```

The question handles this `[->] (input y) -- node {$y$} node[pos = .95] {$-$} (sum);` line. It is possible to reduce this line to one `node` statement, with:

1. Auto labeling for the `y`.
2. The `-` gets its own aligning by `pos = .95`.

Thank you for your effort in advance!