Counting the number of periods (not days) of absence in Excel

Hi Everyone,

I'm putting together an absence spreadsheet, but I want a formula that will calculate the number of periods of absence (rather than number of individual days). e.g. Person A was off from 1 Oct-3 Oct, then on 14 Oct to 20 Oct. This person would have 10 days of absence for the month, but this would be 2 periods.

Any ideas?

PS. I'm using Excel 2007