C# and Excel question

Question

Hello all, I am reading into a listview Excel spread sheets. Using the line: for (int i = 3; i <= 1000; i++) //to loop to 1000 lines Because of varying number of lines per worksheet, how can I read to "end of data"? Another problem I am having is trying to read only certain columns i.e. columns A-F, J-M using : Excel.Range range = worksheet.get_Range("A"+i.ToString(),"O"+i.ToString()); Im working. Any suggestions to read individual columns?