Counting number of items per container including dublicates

Hi, I am trying to create formula that would count the number of item codes that are in same container.
As you can see in the screenshot. My desired end result would be values on the most right side of the screenshot.
As an example container YHXU5000404 has 4 item codes assigned to it. So desired result for that container is 4. It needs to include even if same item code is repeated multiple times.
Since that indicated that order for that item was packed to multiple boxes.
I am new to excel so I am not sure what kind of formula I would need to write for this.

The reason why I need these numbers so that I could create new category for item codes which would be.
If number of item codes in container is 1-25 then = "Low"
If number of item codes in container is 26-50 then = "Medium"
If number of item codes in container is 50+ = "High"

 
Please let me know if there are any questions.