Macro: Insert blank row variable n times

Hello,

I am building a University Timetable. Each subject we offer occupies one row on an excel spreadsheet, we have about 200 subjects in total. Each row inlcudes a value in column M, which is how many tutorials should be scheduled. This value can be anywhere from 1 to 20, or could be blank if the subject has no tutorials.

I would like an excel macro which inserts n number of rows under each row, where n is the value in column M.

Ideally it would cycle through each subject inserting n rows based on column M, all the way to the bottom.

Kind thanks if you can help