Numbers formula for total days between 2 dates including 1st and last

datedif gives the difference between 2 dates .....datedif 01/01/2023 01/09/2023 D is 8

but I want to include the 1st and last day so 9 days

I can't find a formula in HELP & I've checked various sites on Numbers but no dice

Any help with the Numbers formula would be helpful

Thanks