How is the number of prepared spells for a paladin calculated?

PHB p.84 tells us that

You prepare the list of paladin spells that are available for you to cast, choosing from the paladin spell list. When you do so, choose a number of paladin spells equal to your Charisma modifier + half your paladin level, rounded down (minimum of one spell).

This is somewhat ambiguous: it’s not clear whether the number is

floor( (CHA + PL) / 2 ) 

—as seems to be implied by the usage of a comma— or

floor( CHA + (PL/2) ) 

—which would make Charisma investment much more worthwhile.

Which is it? Does a 2nd-level paladin with a 16 Charisma get 2 prepared spells (first formula) or 4 (second)?