how to get rolling periods from a date column in INT data typre

[damzI]

Hello All,
I have the date column in the YYYYMM format but it is in the INT data type.
I am trying to get the date range for 3, 6, and 12 months based on a date selection.

So I have 2 prompts -
the first being the month selection in the YYYYMM format (but it is in the INT type); (eg, 201606 is in the INT data type)
the second being the Rolling Period selection for 3, 6 or 12 months based on the date selected.

I am unable to use the regular date functions like _first_of_month, _last_of_month to get the return values for the filters for the report query.
How can I filter my report on the rolling periods with the above ?