Document document = wordProcessor.Document;
document.LoadDocument("Grimm.docx");
document.InsertSection(document.Range.Start);

//Specify a regular expression that will find all six letter words.
System.Text.RegularExpressions.Regex expr = new System.Text.RegularExpressions.Regex("\\b\\w{6}\\b");
System.Collections.Specialized.StringCollection sixLetterWords = new System.Collections.Specialized.StringCollection();

//Perform the search.
DocumentRange[] found = document.FindAll(expr);
foreach (DocumentRange r in found)
{
  sixLetterWords.Add(document.GetText(r));
}
document.BeginUpdate();

//Insert an ordered list of non-repetitive words in the beginning of the document.
var distinctWords = sixLetterWords.Cast<string>().Distinct().OrderByDescending(s => s);
foreach (var s in distinctWords)
{
  document.InsertText(document.Range.Start, s.ToString() + Environment.NewLine);
}
document.EndUpdate();

Private Sub SurroundingSub()
Dim document As Document = wordProcessor.Document
document.LoadDocument("Grimm.docx")
document.InsertSection(document.Range.Start)

'Specify a regular expression that will find all six letter words. 
Dim expr As System.Text.RegularExpressions.Regex = New System.Text.RegularExpressions.Regex("\b\w{6}\b")
Dim sixLetterWords As System.Collections.Specialized.StringCollection = New System.Collections.Specialized.StringCollection()

'Perform the search. 
Dim found As DocumentRange() = document.FindAll(expr)
For Each r As DocumentRange In found
    sixLetterWords.Add(document.GetText(r))
Next

document.BeginUpdate()

'Insert an ordered list of non-repetitive words in the beginning of the document.
Dim distinctWords = sixLetterWords.Cast(Of String)().Distinct().OrderByDescending(Function(s) s)
For Each s In distinctWords
  document.InsertText(document.Range.Start, s.ToString() + Environment.NewLine)
Next
document.EndUpdate()
End Sub