Convert it to c#

Question

ActiveDocument.Fields.item(f).Type = 64

 

here I tried.

 

Microsoft.Office.Interop.Word.Application app = Globals.ThisAddIn.Application;

Microsoft.Office.Interop.Word.Document doc1 = app.ActiveDocument;

doc1.Fields[f].Parent.Type=64

 

Please send me the code in c#. Its urgent