Thanks for the answer.
Using index.md inside C give me A/index.html but I need to have A/B/C/index.html, I used nested folders, because I want to have more keywords in my urls. seo thing I mean.
How I can get that URL but not that empty/extra index.htmls.
It’s bad practice to have a directory without an index file in it, and even worse to add directories that aren’t needed. Search engines are likely to lower your ranking for that.
If you really want keywords in your URL, then have one directory named A-B-C not three nested ones to give you A/B/C (unless you have content for A or B too).