Exactly!

ok, I got it.
+d //converting a string to number
|| 0 //if there was no number inside that string, it gives us 0, instead of NaN.

Can you please explain why do we use AND here and what is happening in this part? Thank you!
n &&

upd: found a solution, so here if n is falsey we just return false before executing the second part.

Maybe because you didn't use the initial value.

Sounds like you used 52 characters...

thanks a lot! It doesn't allow me switch the flag now :(

That's dangerous. If you skip it and the array has a length of one, you'll try to add the first element with undefined. So it's better practices to add it anyway (only case where you can forget it is when you're absolutely sure there are at least 2 elements.

What you cannot skip, tho: the spoiler flag. ;p

I have got an error - 9 characters is too long.
But the description says that the maximum length is 43 chars.

Thanks! That's the best answer!