Dynamically defaulting the date range prompt

[chandanrock]

Hi All,
I have tried for a solution but failed to get one.

I am using Cognos 10.1 and there is a requirement to default the dates in the date range prompt to 'first of last month' and the 'last of last month'.
Please note im using the following filter in the query --- [Date] in_range ?date?.

For example.
If i am running the report on 'May 1st', the date on the prompt should show 'from date' = apr 01 and 'to date' = 30th apr.

Thanks for your help.
Naga