Welcome to the board.
One way might be to use data validation. For example, say the cell with the count in is C1.
Select A1.
Invoke Data Validation
Settings (tab) Allow: Custom
Formula: =ROW(A1)<=$C$1
Click OK
Now copy A1.
Select the range in column A that you want this to apply to (e.g. A1:A100).
Paste Special > Validation
Inputting 10 will only allow A1:A10 to be edited.
In Excel 97-2003, on the worksheet menu go Data > Validation.
In 2007-2010, on the ribbon go Data > Data Validation.
The 1st tab of the dialog is called 'Settings'.
In that tab choose 'Custom' from the 'Allow' drop-down.
Then, in the 'Formula' text box enter the formula that I provided.
Hope this helps.