What is the easiest way to vertically align overbraces in math? In the following example...
\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{math}
*(m, n) = (\overbrace{n - m}^\text{index}, \overbrace{\sum_{k=m}^{n-1}{\pi_{i_k}}}^\text{sum})
\end{math}
\end{document}
...because the second tuple element has greater vertical extent (due to the summation), the brace appears higher than the other one. I would like to have "index" and "sum" on the same baseline: