How to add Notes to a particular slide in a ppt?

This is working for me please check with this code. Thanks

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using DocumentFormat.OpenXml.Packaging;
using P = DocumentFormat.OpenXml.Presentation;
using A = DocumentFormat.OpenXml.Drawing;
using DocumentFormat.OpenXml;
using DocumentFormat.OpenXml.Presentation;
using DocumentFormat.OpenXml.Drawing;

namespace MadanUpdateNotes
{
class Program
{
static void Main(string[] args)
{
string filePath = @"D:\backup\final.pptx";
AddNote(filePath, 0);
}

public static void AddNote(string docName, int index)
{
using (PresentationDocument ppt = PresentationDocument.Open(docName, true))
{
// Get the relationship ID of the first slide.
PresentationPart part = ppt.PresentationPart;
OpenXmlElementList slideIds = part.Presentation.SlideIdList.ChildElements;

string relId = (slideIds[index] as SlideId).RelationshipId;

// Get the slide part from the relationship ID.
SlidePart slide = (SlidePart)part.GetPartById(relId);

// Build a StringBuilder object.
StringBuilder paragraphText = new StringBuilder();

Console.WriteLine("***************************************************");
Console.WriteLine("Enter the text you want to update");
Console.WriteLine("***************************************************");
string Userdata = Console.ReadLine();
Console.WriteLine("\n");
NotesSlidePart notesSlidePart1;
string existingSlideNote = string.Empty;
string finalNotes = string.Empty;
string Message = string.Empty;

if (slide.NotesSlidePart != null)
{
//Appened new note to existing note.
existingSlideNote = slide.NotesSlidePart.NotesSlide.InnerText + "\n";
Console.WriteLine("***************************************************");
Console.WriteLine("Available notes in this slide is : {0}", slide.NotesSlidePart.NotesSlide.InnerText);// Get the inner text of the slide:
Console.WriteLine("***************************************************");
Console.WriteLine("\n");
Console.WriteLine("***************************************************");
Console.WriteLine("Do you want to Override/Append(Y/N):");
Console.WriteLine("***************************************************");
string YesOrNo = Console.ReadLine();
Console.WriteLine("\n");

if (YesOrNo.ToLower() == "y")
{
finalNotes = Userdata;
Message = "Notes overrided successfully";
}
else
{
finalNotes = existingSlideNote + Userdata;
Message = "Notes appended successfully";
}

var val = slide.NotesSlidePart;
notesSlidePart1 = slide.AddPart<notesslidepart>(val);
}
else
{
//Add a new noteto a slide.
notesSlidePart1 = slide.AddNewPart<notesslidepart>(relId);
finalNotes = Userdata;
Message = "Notes added successfully";
}

NotesSlide notesSlide = new NotesSlide(
new CommonSlideData(new ShapeTree(
new P.NonVisualGroupShapeProperties(
new P.NonVisualDrawingProperties() { Id = (UInt32Value)1U, Name = "" },
new P.NonVisualGroupShapeDrawingProperties(),
new ApplicationNonVisualDrawingProperties()),
new GroupShapeProperties(new A.TransformGroup()),
new P.Shape(
new P.NonVisualShapeProperties(
new P.NonVisualDrawingProperties() { Id = (UInt32Value)2U, Name = "Slide Image Placeholder 1" },
new P.NonVisualShapeDrawingProperties(new A.ShapeLocks() { NoGrouping = true, NoRotation = true, NoChangeAspect = true }),
new ApplicationNonVisualDrawingProperties(new PlaceholderShape() { Type = PlaceholderValues.SlideImage })),
new P.ShapeProperties()),
new P.Shape(
new P.NonVisualShapeProperties(
new P.NonVisualDrawingProperties() { Id = (UInt32Value)3U, Name = "Notes Placeholder 2" },
new P.NonVisualShapeDrawingProperties(new A.ShapeLocks() { NoGrouping = true }),
new ApplicationNonVisualDrawingProperties(new PlaceholderShape() { Type = PlaceholderValues.Body, Index = (UInt32Value)1U })),
new P.ShapeProperties(),
new P.TextBody(
new A.BodyProperties(),
new A.ListStyle(),
new A.Paragraph(
new A.Run(
new A.RunProperties() { Language = "en-US", Dirty = false },
new A.Text() { Text = finalNotes }),
new A.EndParagraphRunProperties() { Language = "en-US", Dirty = false }))
))),
new ColorMapOverride(new A.MasterColorMapping()));

notesSlidePart1.NotesSlide = notesSlide;
Console.WriteLine("***************************************************");
Console.WriteLine(Message);
Console.WriteLine("***************************************************");
Console.ReadLine();

}
}
}
}