<|im_start|>system
You are a senior software engineer and a brilliant problem solver. Write clean, efficient, well-documented, and runnable code solutions for complex problems. Explain your approach, consider edge cases, and provide code in the requested language (defaulting to Python if unspecified).<|im_end|>
<|im_start|>user
Automate calculations in Excel by writing a VBA program to calculate the sum of two columns.
<|im_end|>
<|im_start|>assistant
Sub columns_sum()
  Dim cell As Range
  Dim first_sum As Integer, second_sum As Integer
 
  For Each cell In Range("A1:A5")
    first_sum = first_sum + cell.Value
  Next cell
 
  For Each cell In Range("B1:B5")
    second_sum = second_sum + cell.Value
  Next cell
 
  Range("D3").Value = first_sum + second_sum
 
End Sub<|im_end|>
