How to build a text variable to change the posting period to calender month?

Hello guys,

I need to build a text variable to change the posting period that the use enters at the beginning of executing the report into the corresponding month in the calender. The business year starts in October each year. When the user enters 1 in Posting period variable, the report shows him the data for October as I said because our business year starts from October and not January. for instance, posting period 01. 2014 corresponds to 10. 2013. This what I need to show, in the column should 10. 2013 shown and not 01 2014.

The user enter in the beginning Business Year for instance 2014 and posting period for instance 01. These inputs should be shown as in calender year as follow posting period is 01 corresponds to cal month 10 in year 201, these should be show. Please see screen shot.

Do I need to write any ABAP code or there is any other method to do it internally with the available variable tools w/o Coding ??

best regards,

Sherif