Compare Paragraph Styles

[ricky_cpp]

Hi,

I am writing a word document using C#. At some point, I have to see if a heading is already archived in word, so that I can skip writing it again. My problem is
1. I can not iterate through headings in a word document.
2. If I iterate through paragraph and try to compare if its heading is same Word.WdBuiltinStyle.wdStyleHeading1, it returns me an error that unboxing in this format is not possible.

Below is the code:

object headingStyle = Microsoft.Office.Interop.Word.WdBuiltinStyle.wdStyleHeading1;
foreach (Word.Paragraph para in mTdbDoc.Paragraphs)
{
     Word.WdBuiltinStyle style = (Word.WdBuiltinStyle)para.get_Style();  //Error here
         if (style.Equals(headingStyle))
            if (para.Range.Text.StartsWith(aCompareString))
                 return para.Range.End;
}
            return -1;

I do not want to do it with Syle.NameLocal because it differs on different machines depending on the word language.

Any hint will be helpful.

Regards
Ricky