No. of Row = No. of inputs

Hi guys, Hope you can help with my situation.
Here's the scenario I need to create a vba macro that can place a constant text in other column.
For example,
Excel.JPG
as you can see in the attachment, the no. of text("TC") proportional to the no. of Row in column A.
this column A and the no of Row will be user input. As long as the user input more row in Column A it will also generate a text("TC") every 3 row

Hoping for the best and thank you in advance