isi entrance problem

The following figure shows a $3^2*3^2$ grid divided into $3^2$ subgrids of size 3*3 . This grid has 81 cells , 9 in each subgrid .Now consider an $n^2*n^2$ grid divided into $n^2$ subgrids of size n*n . Find the number of ways in which you can select $n^2$ cells from the grid such that there is exactly one cell coming from each subgrid , one from each row and one from each column.

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