How to get row count in table visual

Hi Team,

I need a measure that will give the count of rows from the table visual.

In the requirement, the user is selecting TOP N values from the TOP N filter and I want to show the same value in a measure that ' User has selected 5 values in the TOP N filter based on another measure.

I know we will not access the values user will enter in TOP N filter but how to get row count in visual?

An alternative solution in my requirement is the Measure should show DistinctCount Opptinumber values i.e 5 

Sample Data in table 

Oppty number    BU   Sales

1                          S    20

2                          A     30

3                           F      40

3                           P        50

3                           S         89

4                           A         30

5                            Au       40

Please help me with the implementation.

Regards,

Rajesh