How do I upload image on imgur from url C#

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C#

Hi,
I have tried to upload images on imgur.com using this code below
It works for few times but it returns 429 error- too many requests
Is it possible to upload images from other url on imgur progrmmatically using c#?

private string upload_img_from_url(string old_img_url)
{

string new_img_url = "";

string key = "<<<my key="" is="" here="">>>";

try
{
using (WebClient client = new WebClient())
{
client.Headers.Add("Authorization", "Client-ID " + key);
string response = client.DownloadString("http://imgur.com/upload?url=" + old_img_url);

response = response.Substring(response.IndexOf("<link rel=\"image_src\""), response.IndexOf("


string str_href = "href=\"(.*)\"";
Match match = Regex.Match(response, str_href);
if (match.Success)
{
new_img_url = match.Groups[1].Value;

}
}
}
catch (Exception ex)
{
txt_ssulf_error.Text = ex.Message;
}

return new_img_url;
}

What I have tried:

I have tried to upload using old api version
the url was http://imgur.com/api/upload?url=<<the image url>>
But it returns 404 error