use long as return type for count

[rtroilo]

As it is not predictable how many thing needs to be counted, use the largest type (long) for counting.

Checklist

• [x] My code follows the code-style rules, and I have checked on the static analyses and benchmark (if applicable) results
• ~I have commented my code~
• ~I have written javadoc (required for public classes and methods)~
• [x] I have added sufficient unit tests
• [ ] I have made corresponding changes to the documentation
• [ ] I have updated the CHANGELOG.md
• [ ] I have adjusted the examples or created an issue in the corresponding repository
• [ ] I have adjusted the benchmark or created an issue in the corresponding repository