Counting Unique Values on Multiple Criteria

I've been faced with this dilemna for 3 days now. I have a table of data with duplicate information wherein I need to count each occurence of each duplicate in a single column only once based on 4 different criteria.

Sample file is attached in .xlsx format.

Blue columns represent the criteria and Yellow column represents what I'm counting. I've been using COUNTIFS based on the criteria, but it doesn't count unique values.

Your help is appreciated.

pt