split image into 4 equal parts

[Perfecto]

Hi,
split image into 4 equal parts :

I couldn't find any way to do it via the actions.
So I coded this script in C#

string imageURL = project.Variables["imageURL"].Value;
string SaveImagePath = project.Variables["SaveImagePath"].Value;

void DivideAndSaveImage()
{
    if (string.IsNullOrEmpty(imageURL))
    {
        project.SendInfoToLog("The image URL cannot be empty", "Error in imageURL");
        return;
    }

    string outputDirectory = Path.Combine(SaveImagePath, "images");

    if (!Directory.Exists(outputDirectory))
    {
        Directory.CreateDirectory(outputDirectory);
    }

    using (Image image = DownloadImageFromUrl(imageURL))
    {
        int width = image.Width / 2;
        int height = image.Height / 2;

        Rectangle[] sections =
        {
            new Rectangle(0, 0, width, height),
            new Rectangle(width, 0, width, height),
            new Rectangle(0, height, width, height),
            new Rectangle(width, height, width, height)
        };

        for (int i = 0; i < sections.Length; i++)
        {
            string savePath = Path.Combine(outputDirectory, $"part{i + 1}.jpg");
            SaveImageSection(image, sections[i], savePath);
        }
    }
}

Image DownloadImageFromUrl(string imageUrl)
{
    Image image;
    using (WebClient webClient = new WebClient())
    {
        byte[] imageBytes = webClient.DownloadData(imageUrl);

        using (MemoryStream memoryStream = new MemoryStream(imageBytes))
        {
            image = Image.FromStream(memoryStream);
        }
    }
    return image;
}

void SaveImageSection(Image image, Rectangle rect, string savePath)
{
    using (Bitmap bmp = new Bitmap(rect.Width, rect.Height))
    {
        using (Graphics g = Graphics.FromImage(bmp))
        {
            g.DrawImage(image, 0, 0, rect, GraphicsUnit.Pixel);
        }
        bmp.Save(savePath);
    }
}

but it returns this error:

Compiling code of Error in action "CS0246" "The type or namespace name 'WebClient' could not be found (are you missing a using directive or an assembly reference?)". [Row: 43; Column: 12]
Compiling code of Error in action "CS0246" "The type or namespace name 'WebClient' could not be found (are you missing a using directive or an assembly reference?)". [Row: 43; Column: 38]

While I have imported System.Net 4.0