Document doc1 = new Document();
doc1.LoadFromFile(inputFile2);
Document doc2 = new Document();
doc2.LoadFromFile(inputFile1);
doc1.Compare(doc2, "summer");
doc1.SaveToFile(outputFile);
doc1.Dispose();

table.TableFormat.Positioning.ClearFormatting().

Presentation presentation = new Presentation();
presentation.LoadFromFile(pptfile);
ISlide slide = presentation.Slides[0];
//Add section 
presentation.SectionList.Add("section1", slide);
//Get section
Section section;
String name;
  for (int i = 0; i < presentation.SectionList.Count; i++)
    {
      section  = presentation.SectionList[i];
      name = section.Name;
         foreach (long id in section.SlideIdList)
          {
           }
     }

ISmartArt smartArt = presentation.Slides[0].Shapes[0] as ISmartArt;
int count =smartArt.Nodes.Count;
ISmartArtNode node;
  for (int i = 0; i < count; i++)
    {
    node = smartArt.Nodes[i];
    node.Line.FillType = FillFormatType.Solid;
    node.Line.SolidFillColor.Color = Color.Gray;
    node.Line.Width = 2;
    }

ISmartArt smartArt = presentation.Slides[0].Shapes[0] as ISmartArt;
int count =smartArt.Nodes.Count;
ISmartArtNode node;
  for (int i = 0; i < count; i++)
    {
    node = smartArt.Nodes[i];
    node.LinkLine.FillType = FillFormatType.Solid;
    node.LinkLine.SolidFillColor.Color = Color.Gray;
    node.LinkLine.Width = 2;
    node.LinkLine.DashStyle = LineDashStyleType.SystemDash;
    }