Detect unique values in cell and find them in column to count them

Hi everyone!

It's the first time I come in here to ask a question so first of all my apologies if I am missing something when I describe my question.

I am trying to figure out a way to do the following:

Newpic.JPG

I want to create a function or something that allows me to detect the Project Numbers and see if they have previously been entered. If several projects are entered in one cell, they will be separated by a /. If project numbers have not been previously entered all should be counted in column "Number" as shown in the picture.

Does someone have an idea on how to do such thing?

Any help will be much appreciated.
Thanks.