How to group date in Google analytics?

Question

Google Analytics

I have a page traffic report. All pages in this format

/page/category-1/category-1-subcategory-1
/page/category-2/category-2-subcategory-1
/page/category-1/category-1-subcategory-2

And there are infinitely many such categories and subcategories. I want to get a report with the number of views by category, without taking into account sub-categories (total for all sub-categories).
For example:

/page/category-1/category-1-subcategory-1 = 150
/page/category-2/category-2-subcategory-1 = 100
/page/category-1/category-1-subcategory-2 = 50

I want to get a report like this

[category-1] = 200
[category-2] = 100

Answer 1

API
well, or regular expressions in the interface, what the heck is there now

Answer 2

There is one way to do this, but not sure about hindsight.
We go to the "Content Groups" section and create a group according to your categories.
After that, you will have the opportunity to select this group in the page traffic report
. group as you like