Formula - Efficient way to assign signs (+/-) to numbers in alternating in a column

[Cubist]

I'm looking for an efficient way to turn column A into column B. I have a few ideas but what's the most efficient?

Book1
	A	B
1	From	To
2	+	5
3	5	2
4	+	-1
5	2	-8
6	-
7	1
8	-
9	8
Sheet13

 

[Joe4]

At that moment, I had access only to Excel 2021, which is lacking many new functions

I am just having some fun and giving you a hard time!
I thought it was funny how you started your 2nd post with "Why not just...", when you had already posted a different answer too!

Seriously though, it is a cool, easy way to do it taking advantage of some of the new functions.
You taught me something new today!