How do I run diskpart from c# and hide the window?

Here is my code:

Process p = new Process();
p.StartInfo.UseShellExecute = false;
p.StartInfo.WindowStyle = ProcessWindowStyle.Hidden;
p.StartInfo.RedirectStandardOutput = true;
p.StartInfo.FileName = @"C:\Windows\System32\diskpart.exe";
p.StartInfo.RedirectStandardInput = true;
p.Start();
p.StandardInput.WriteLine("select disk " + diskNumber);
p.StandardInput.WriteLine("clean");
p.StandardInput.WriteLine("active");
p.StandardInput.WriteLine("assign");         
p.StandardInput.WriteLine("exit");
string output = p.StandardOutput.ReadToEnd();
p.WaitForExit();

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As you see, I have taken a step to make the window hidden. But it still appears.
Any trick to make it actually hide and never show, and still run the code?