Excel - Multiplying daily values for each week

Here's how my table layout looks

What I have: over 200 rows, each with three values, each for a unique day. Only values for workdays are listed, so sometimes there may be days or even whole weeks missing from the list because of holidays.

What I need: for every finished week that had at least one daily row (and therefore the day was present on the list) I need to multiply the values from the column DIF (The formula looks like =(1-ValueDayOne)*(1-ValueDayTwo)-1) and then create a list of those weekly values.

Could anyone help me with that? If anything I wrote is not 100% clear feel free to ask questions, I tried to specify all the required information but I may have accidentally omitted something.