Alternative to nested IF's : INDEX/MATCH to gather data into one column ?

Hi,

My worksheet has about 15 columns of input from different users (Yes or No). I would like to gather all this input into a single column. I can't used nested IF's using OR since I can't go over seven IF's.

So I need a formula in my master column to :

1) Determine if column has Y or N if so go to next line
2) Determine if column is empty if so, go to next column. If last column is empty then do nothing

I've tried using INDEX/MATCH or INDEX/OFFSET but it seems you need an outside reference for the lookup. Anyways I've attached a spreadsheet to make myself clearer.

Thanks,
amphinomos