LaTeX倾斜标注

\documentclass{ctexart}
\usepackage{amsmath}
\usepackage{tikz}
\usetikzlibrary{decorations.pathreplacing}
\newcommand\tikzmark[2][0,0]{%
\tikz[baseline,remember picture,overlay]
\coordinate (#2) at (#1);}
\begin{document}
$k$个$k$个$k$个$k$个$k$个$k$个$k$个$k$个$k$个$k$个$k$个$k$个$k$个$k$个$k$个$k$个$k$个$k$个$k$个$k$个$k$个$k$个$k$个
\[
A_{km}(x)=2^{
\tikzmark[0pt,4.5pt]{C1}
2^{2^{\cdot^{\cdot^{\cdot^{
\tikzmark[2pt,4pt]{C2}
2^{x^{
\tikzmark[0pt,3.5pt]{C3}
2^{2^{\cdot^{\cdot^{\cdot^{
\tikzmark[2pt,4pt]{C4}
2}}}}}}}}}}}}},
B_k(y)=4^{
\tikzmark[0.5pt,4pt]{B1}
4^{4^{\cdot^{\cdot^{\cdot^{
\tikzmark[2pt,4pt]{B2}
4^y}}}}}}.
%
\tikz[remember picture,overlay]
{
\draw[decorate,decoration=brace]
(C1)--node[shift={(135:8pt)}]{$\scriptstyle k\text{个}$}(C2);
\draw[decorate,decoration=brace]
(C3)--node[shift={(135:8pt)}]{$\scriptstyle m\text{个}$}(C4);
\draw[decorate,decoration=brace]
(B1)--node[shift={(135:8pt)}]{$\scriptstyle k\text{个}$}(B2);
}
\]
$k$个$k$个$k$个$k$个$k$个$k$个$k$个$k$个$k$个$k$个$k$个$k$个$k$个$k$个$k$个$k$个$k$个
\end{document}