Calculation of Dates

I have to prepare fortnightly expense statement which is updated on daily basis. Sample workbook is enclosed.

I just laid the data in Cells C5:C6, while these are calculated on parameter in Cell c3 where 1 represent 1st fortnight and 2 represent 2nd fortnight. (in the attached sample workbook)

I look forward to a formula or formulas that automatically update headings in Cell C5 & C6. For Sample purpose, I assume that report for 1st fortnight is prepared on Jan 13, 2017 while for 2nd fortnight report is prepared on Jan 22, 2017. While my requirement is that these dates are calculated automatically either by Today() formula or any other better option.