Help with the simplest of problems - subtraction

Hi there,
I’m being driven crazy by a very straightforward problem. The issue isn’t the logic as much as it is figuring out how to accomplish what I need with Hubl.
I have an array (list) of numbers. I’m trying to accomplish the hubl equivalent of Javascript’s += addition assignment.

{% set bee = 10 %}
{% set sees = [1, 2, 3] %}
{% for see in sees %}
{% do bee = bee - see %}
{{ bee }}
{% endfor %}
{{ bee }}

I want 10 to equate to:
1. First loop: 10 - 1 = 9.
2. Second loop: 9- 2 = 7.
3. Third and final loop: 7 - 3 = 4.
bee = 4. That’s all I want.
I’m also getting the baffling error that can be seen in the screenshot, which I can’t begin to comprehend. I’ve tried to use the |int filter in case the integer wasn’t being processed as an integer.
Someone please put me out of my misery. How do I do this with Hubl? I can accomplish with JS, but I think I’m just missing something here.
I would really, really appreciate any feedback - particularly the helpful kind.
Thank you!

I’m not so happy to report that I’ve found the “sum” filter after losing hours to this. Hopefully this post helps save someone else from the same fate.