Display report subtotal ONLY if multiple values are selected from the dashboard prompt

Hi all - Good afternoon

Of late I attended one technical interview and was asked to solve one scenario. The scenario was : 
   " I have a dashboard prompt on one column say Country. I want to show the subtotal if i select more than one country in the prompt otherwise the report should not have subtotal " - I took my own time but could not answer the question :-( 

Finally I decided to figure out this issue practically and found a solution. Enjoy.. I know you have started guessing the solution and might have found some pointers.

Create a simple report - Label it as NoSubtotal.

Create one report - Subtotal - Here we are subtotal option has been enabled in the table view.

Create one intermediate report - Prod Category Prompt report

Now we have to create a prompt on Product Category and give the reference of presentation variable A.

Now let us go to the dashboard editor and make use of section condition and intermediate report.

Save the changes and test the dashboard. 

Thank you. 
 It might help some of you if by chance you come across with such type of scenario question in an interview process. :-)  Good Luck.