Return Count of Instances of Strings in a Column Matching List of Strings in Another Column

I'm looking for a formula that can be applied to a column that will return the count of instances of strings defined in another column. Refer to the attached example:

Example.xlsx

Ex. 1 should return 6 because there is 2 instances of item1, 2 instances of item2, and 2 instances of item9. Item3 and item4 are not included in the count because they are not in the Criteria column.

Any questions let me know!