How can I represent Multidimensional array in msg format

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If i have something like

int  mein[NUM][4];

in C++. How do I represent it in msg format. Should it be something like

uint8[][4] mein

Also as NUM is defined in my C++ file and can vary according to certain parameters. Should I just allocate it dynamically in msg format or I should give it a certain value or define NUM in msg format. Do you think there would be any disadvantage if I just allocate it dynamically meaning like uint8[][4] mein.