Moving Averages

Hi,

I am trying to create a formula that will dynamically calculate a short-run and long-run moving average. The number of periods for each moving average can change depending on what is typed into cell C2 and cell C3.

For example, if $C$2=2, then the SRMA in cell E8 would be the average for Periods 1-2, or 594,443 (average of cells D7:D8). If $C$2=3, then cell E8 would be empty and cell E9 would be 602,394.

Thanks so much!
John