Move a slide to a new position in a presentation

class Program
    {
        static void Main(string[] args)
        {
            MoveSlide(@"..\..\Documents\Myppt13.pptx", 0, 1);
        }
        // Counting the slides in the presentation.
        public static int CountSlides(string presentationFile)
        {
            // Open the presentation as read-only.
            using (PresentationDocument presentationDocument = PresentationDocument.Open(presentationFile, false))
            {
                // Pass the presentation to the next CountSlides method
                // and return the slide count.
                return CountSlides(presentationDocument);
            }
        }

        // Count the slides in the presentation.
        public static int CountSlides(PresentationDocument presentationDocument)
        {
            // Check for a null document object.
            if (presentationDocument == null)
            {
                throw new ArgumentNullException("presentationDocument");
            }

            int slidesCount = 0;

            // Get the presentation part of document.
            PresentationPart presentationPart = presentationDocument.PresentationPart;

            // Get the slide count from the SlideParts.
            if (presentationPart != null)
            {
                slidesCount = presentationPart.SlideParts.Count();
            }

            // Return the slide count to the previous method.
            return slidesCount;
        }

        // Move a slide to a different position in the slide order in the presentation.
        public static void MoveSlide(string presentationFile, int from, int to)
        {
            using (PresentationDocument presentationDocument = PresentationDocument.Open(presentationFile, true))
            {
                MoveSlide(presentationDocument, from, to);
            }
        }
        // Move a slide to a different position in the slide order in the presentation.
        public static void MoveSlide(PresentationDocument presentationDocument, int from, int to)
        {
            if (presentationDocument == null)
            {
                throw new ArgumentNullException("presentationDocument");
            }

            // Call the CountSlides method to get the number of slides in the presentation.
            int slidesCount = CountSlides(presentationDocument);

            // Verify that both from and to positions are within range and different from one another.
            if (from < 0 || from >= slidesCount)
            {
                throw new ArgumentOutOfRangeException("from");
            }

            if (to < 0 || from >= slidesCount || to == from)
            {
                throw new ArgumentOutOfRangeException("to");
            }

            // Get the presentation part from the presentation document.
            PresentationPart presentationPart = presentationDocument.PresentationPart;

            // The slide count is not zero, so the presentation must contain slides.            
            Presentation presentation = presentationPart.Presentation;
            SlideIdList slideIdList = presentation.SlideIdList;

            // Get the slide ID of the source slide.
            SlideId sourceSlide = slideIdList.ChildElements[from] as SlideId;

            SlideId targetSlide = null;

            // Identify the position of the target slide after which to move the source slide.
            if (to == 0)
            {
                targetSlide = null;
            }
            if (from < to)
            {
                targetSlide = slideIdList.ChildElements[to] as SlideId;
            }
            else
            {
                targetSlide = slideIdList.ChildElements[to - 1] as SlideId;
            }

            // Remove the source slide from its current position.
            sourceSlide.Remove();

            // Insert the source slide at its new position after the target slide.
            slideIdList.InsertAfter(sourceSlide, targetSlide);

            // Save the modified presentation.
            presentation.Save();
        }
    }