\documentclass[a4paper]{article}

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\newcommand{\IG}[1]{%
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\begin{document}

\begin{figure}
  \centering
  \IG{graphs/R1-10:1-cluster-line.pdf}%
  \IG{graphs/R1-10:1-cluster-torus.pdf}%
  \IG{graphs/R1-10:1-cluster-hcube.pdf}%

  \IG{graphs/R1-10:1-grid-line.pdf}%
  \IG{graphs/R1-10:1-grid-torus.pdf}%
  \IG{graphs/R1-10:1-grid-hcube.pdf}%

  \IG{graphs/RN-10:1-cluster-line.pdf}%
  \IG{graphs/RN-10:1-cluster-torus.pdf}%
  \IG{graphs/RN-10:1-cluster-hcube.pdf}%

  \IG{graphs/RN-10:1-grid-line.pdf}%
  \IG{graphs/RN-10:1-grid-torus.pdf}%
  \IG{graphs/RN-10:1-grid-hcube.pdf}%

  \caption{Real mode, comp/comm ratio${} = 10:1$.}
\end{figure}
\clearpage

\begin{figure}
  \centering
  \IG{graphs/R1-1:1-cluster-line.pdf}%
  \IG{graphs/R1-1:1-cluster-torus.pdf}%
  \IG{graphs/R1-1:1-cluster-hcube.pdf}%

  \IG{graphs/R1-1:1-grid-line.pdf}%
  \IG{graphs/R1-1:1-grid-torus.pdf}%
  \IG{graphs/R1-1:1-grid-hcube.pdf}%

  \IG{graphs/RN-1:1-cluster-line.pdf}%
  \IG{graphs/RN-1:1-cluster-torus.pdf}%
  \IG{graphs/RN-1:1-cluster-hcube.pdf}%

  \IG{graphs/RN-1:1-grid-line.pdf}%
  \IG{graphs/RN-1:1-grid-torus.pdf}%
  \IG{graphs/RN-1:1-grid-hcube.pdf}%

  \caption{Real mode, comp/comm ratio${} = 1:1$.}
\end{figure}
\clearpage

\begin{figure}
  \centering
  \IG{graphs/R1-1:10-cluster-line.pdf}%
  \IG{graphs/R1-1:10-cluster-torus.pdf}%
  \IG{graphs/R1-1:10-cluster-hcube.pdf}%

  \IG{graphs/R1-1:10-grid-line.pdf}%
  \IG{graphs/R1-1:10-grid-torus.pdf}%
  \IG{graphs/R1-1:10-grid-hcube.pdf}%

  \IG{graphs/RN-1:10-cluster-line.pdf}%
  \IG{graphs/RN-1:10-cluster-torus.pdf}%
  \IG{graphs/RN-1:10-cluster-hcube.pdf}%

  \IG{graphs/RN-1:10-grid-line.pdf}%
  \IG{graphs/RN-1:10-grid-torus.pdf}%
  \IG{graphs/RN-1:10-grid-hcube.pdf}%

  \caption{Real mode, comp/comm ratio${} = 1:10$.}
\end{figure}
\clearpage

\begin{figure}
  \centering
  \IG{graphs/I1-10:1-cluster-line.pdf}%
  \IG{graphs/I1-10:1-cluster-torus.pdf}%
  \IG{graphs/I1-10:1-cluster-hcube.pdf}%

  \IG{graphs/I1-10:1-grid-line.pdf}%
  \IG{graphs/I1-10:1-grid-torus.pdf}%
  \IG{graphs/I1-10:1-grid-hcube.pdf}%

  \IG{graphs/IN-10:1-cluster-line.pdf}%
  \IG{graphs/IN-10:1-cluster-torus.pdf}%
  \IG{graphs/IN-10:1-cluster-hcube.pdf}%

  \IG{graphs/IN-10:1-grid-line.pdf}%
  \IG{graphs/IN-10:1-grid-torus.pdf}%
  \IG{graphs/IN-10:1-grid-hcube.pdf}%

  \caption{Integer mode, comp/comm ratio${} = 10:1$.}
\end{figure}
\clearpage

\begin{figure}
  \centering
  \IG{graphs/I1-1:1-cluster-line.pdf}%
  \IG{graphs/I1-1:1-cluster-torus.pdf}%
  \IG{graphs/I1-1:1-cluster-hcube.pdf}%

  \IG{graphs/I1-1:1-grid-line.pdf}%
  \IG{graphs/I1-1:1-grid-torus.pdf}%
  \IG{graphs/I1-1:1-grid-hcube.pdf}%

  \IG{graphs/IN-1:1-cluster-line.pdf}%
  \IG{graphs/IN-1:1-cluster-torus.pdf}%
  \IG{graphs/IN-1:1-cluster-hcube.pdf}%

  \IG{graphs/IN-1:1-grid-line.pdf}%
  \IG{graphs/IN-1:1-grid-torus.pdf}%
  \IG{graphs/IN-1:1-grid-hcube.pdf}%

  \caption{Integer mode, comp/comm ratio${} = 1:1$.}
\end{figure}
\clearpage

\begin{figure}
  \centering
  \IG{graphs/I1-1:10-cluster-line.pdf}%
  \IG{graphs/I1-1:10-cluster-torus.pdf}%
  \IG{graphs/I1-1:10-cluster-hcube.pdf}%

  \IG{graphs/I1-1:10-grid-line.pdf}%
  \IG{graphs/I1-1:10-grid-torus.pdf}%
  \IG{graphs/I1-1:10-grid-hcube.pdf}%

  \IG{graphs/IN-1:10-cluster-line.pdf}%
  \IG{graphs/IN-1:10-cluster-torus.pdf}%
  \IG{graphs/IN-1:10-cluster-hcube.pdf}%

  \IG{graphs/IN-1:10-grid-line.pdf}%
  \IG{graphs/IN-1:10-grid-torus.pdf}%
  \IG{graphs/IN-1:10-grid-hcube.pdf}%

  \caption{Integer mode, comp/comm ratio${} = 1:10$.}
\end{figure}
\clearpage

\end{document}
