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     7 

     7 

     8 \begin{document}

     8 \begin{document}

     9 \thispagestyle{empty}

     9 \thispagestyle{empty}

    10 

    10 

    11 \begin{align*}

    18 \begin{align*}

    12 abmab & \\

    19 abmab & \\

    13 v_1 v_2 v_3 v_4 A

    20 v_1 v_2 v_3 v_4 A

    14 \end{align*}

    21 \end{align*}

    15 \end{document}

    22 \end{document}