rotate pdf even pages

import PyPDF2

def rotate_even_pages(input_pdf, output_pdf):
    # Open the input PDF
    with open(input_pdf, 'rb') as infile:
        reader = PyPDF2.PdfReader(infile)
        writer = PyPDF2.PdfWriter()

        # Iterate over all the pages
        num_pages = len(reader.pages)
        for i in range(num_pages):
            page = reader.pages[i]
            # Rotate only the even pages (index 1, 3, 5, etc.)
            if i % 2 == 1:  # 1-based index for even pages: 2, 4, 6, etc.
                page.rotate(180)
            writer.add_page(page)

        # Write the output PDF
        with open(output_pdf, 'wb') as outfile:
            writer.write(outfile)

# Example usage
input_pdf = 'input.pdf'  # Replace with your input PDF file
output_pdf = 'output.pdf'  # Replace with your desired output PDF file
rotate_even_pages(input_pdf, output_pdf)

print(f"Processed PDF saved as '{output_pdf}'")