How to get Data labels In charts using C#

[C# Programming]

I want to put datalabels and legendkeys in powerpoint using c#. how to achieve this? here is the code below

private void button1_Click(object sender, EventArgs e)
{
String strTemplate;
strTemplate =
"C:\\Program Files\\Microsoft Office\\Templates\\Presentation Designs\\Blends.pot";

PowerPoint.Application objApp;
PowerPoint.Presentations objPresSet;
PowerPoint._Presentation objPres;
PowerPoint.Slides objSlides;
PowerPoint._Slide objSlide;
PowerPoint.TextRange objTextRng;
Graph.Chart objChart;
Graph.DataSheet dataSheet;
//Create a new presentation based on a template.
objApp = new PowerPoint.Application();
objApp.Visible = MsoTriState.msoTrue;
objPresSet = objApp.Presentations;
objPres = objPresSet.Open(strTemplate,
MsoTriState.msoFalse, MsoTriState.msoTrue, MsoTriState.msoTrue);
objSlides = objPres.Slides;
objSlide = objSlides.Add(1, PowerPoint.PpSlideLayout.ppLayoutTitleOnly);
objTextRng = objSlide.Shapes[1].TextFrame.TextRange;
objTextRng.Text = "My Chart";
objTextRng.Font.Name = "Comic Sans MS";
objTextRng.Font.Size = 48;

objChart = (Graph.Chart)objSlide.Shapes.AddOLEObject(150, 150, 480, 320,
"MSGraph.Chart.8", "", MsoTriState.msoFalse, "", 0, "",
MsoTriState.msoFalse).OLEFormat.Object;
dataSheet = objChart.Application.DataSheet;


dataSheet.Cells[1, 2] = "abc";
dataSheet.Cells[2, 2] = "50";
dataSheet.Cells[2, 3] = "40";
dataSheet.Cells[2, 4] = "50";
dataSheet.Cells[2, 5] = "50";
dataSheet.Cells[3, 2] = "60";
dataSheet.Cells[3, 3] = "70";
dataSheet.Cells[3, 4] = "80";
dataSheet.Cells[3, 5] = "60";
dataSheet.Cells[4, 2] = "50";
dataSheet.Cells[4, 3] = "40";
dataSheet.Cells[4, 4] = "50";
dataSheet.Cells[4, 5] = "50";
objChart.Application.Update();

objChart.Legend.Position = Graph.XlLegendPosition.xlLegendPositionBottom;

objChart.HasTitle = true;
objChart.ChartTitle.Text = "Here it is...";

objPres.SaveAs("C:\\abc.ppt", PowerPoint.PpSaveAsFileType.ppSaveAsPresentation, MsoTriState.msoTrue);
objPres.Close();
objApp.Quit();
}