Help with Date Difference Expression

Good morning,

Based on the following:

Lost Days = DateDiff("d",Nz([MyLostDaysBeginDate]),Nz([MyLostDaysEndDate]))

Restricted Days =
DateDiff("d",Nz([MyRestrictedDaysBeginDate]),Nz([MyRestrictedDaysEndDate]))

I need an expression that will subtract the Lost Days from the Restricted
Days, when the Lost Days date range is the same (or between) as the
Restricted Days date range. This will yield total Restricted Days.

Example:

Restricted Days were incurred from 02/01/09 to 03/01/09 and Lost Days were
incurred from 01/01/09 to 02/15/09. The overlap occurs from 02/01/09 to
02/15/09.

How can arrive at the Total Restricted Days?

Thanks in advance for your help,

Rene