how about naming? - c - it's not appropriate to call element like this

Agree!
How are those people who voted this solution with the clever mark??

Agreed!
Absolutely! no doubt!

I saw at least 10 solutions here - and all of them includes methods like splice or slice
and magic numbers like 3

yep!

all the solutions above - includes the number 3 - strange number.

I know, but it's better to write it in one line using js modern methods, than use my own poor mistake decision

but why you don't use v anywhere?
is it correct for 'use strict' mode?

7level ? serously - i've spand about 2 hours to go through it!!!