Please explain how to adjust the NPV function so it does beginning of period discounting and the result

FACT PATTERN 12/31/2013 Free Cash Flow for Lemonade Co. 12/31/2014 12/31/2015 12/31/2016 12/31/2017 12/31/2018 Free Cash Flow 1,000.0 1,000.0 1,500.0 1,250.0 1,500.0 Discount rate 10.00% QUESTION Using an NPV function, what is the cumulative discounted cash flow, assuming beginning of period discounting? Answer Formula How to adjust NPV for beginning of period discounting