There are four choices for the second building block: choose not to choose, choose 1, 2, 3, * * *;
There are four choices for the third building block: select or not, select 1, 2,3 and * * *.
Therefore, the total number of selections is
5×4×4=80 (species)
But among them, choosing none is not up to the requirements.
So, * * * has.
80- 1=79 (type)