Revision 603bb373-bb69-4c76-9ab0-efb025427ce4 - Code Golf Stack Exchange

# [C (gcc)] -lm, <sup><s>23</s> \$\cdots\$ <s>50</s></sup> 27 bytes

Saved 6 bytes thanks to [a'_'](https://codegolf.stackexchange.com/users/85052/a)!!! 
Added 38 bytes to fix type error kindly pointed out by [S.S. Anne](https://codegolf.stackexchange.com/users/89298/s-s-anne). 
Saved 3 bytes thanks to [rtpax](https://codegolf.stackexchange.com/users/85545/rtpax)!!! 
Saved a whopping 23 bytes thanks to an idea from [ErikF](https://codegolf.stackexchange.com/users/79060/erikf)!!! 

<!-- language-all: lang-c -->

 #define f(n)ceil(n/sqrt(2))

[Try it online!][TIO-ki3q59g5]

[C (gcc)]: https://gcc.gnu.org/
[TIO-ki3q59g5]: https://tio.run/##fVJtb4IwEP7ur7iwmIDWWEpLIc59WfYrpllMKY4Mq6OYkRn/@tjxInFLlISj99xz1@fuULOtUnX9kOg0MxpS13hKZ7lr5vazKF3mefVukxnXg9MI8Dkam22NTiDfm21nSm3LN/O6hiXGT5SAT4ARCAhwAgJdhAIEBG1i9GK7QxRyzqUfDlgLM59LHgUhl5hKA4kgj2MsyGIeh5LFWJYLGog4DpnEOKLnxS2BujpoVeqklfhHYKcxIgCs8QQ6kjaupNKneDn4gY86gibcYqGMWAMLP8J@mLgWGw1i21YxkwsmMMJCFkUXgep9U0zQavWhi06Ss6pe2KqKn/EVDoFrP3D6vHRfgJuZEjKT6ArT6KI/PoLNvvU@dS@NevMemAzIAqbTln1Z5I1ZGSzcL7Slrxf32BbZzS9zl6SRNKzgf9FDgS2lrjPO8yPMnqD9ju3K4BgMAUuGSdnlUq/7m86jc/2j0nyztfUs39Wzr18 "C (gcc) – Try It Online"