public void Compare(string orginal, string target)
{
Microsoft.Office.Interop.PowerPoint.Application powerPoint = new Microsoft.Office.Interop.PowerPoint.Application {
Visible = MsoTriState.msoCTrue
};
Microsoft.Office.Interop.PowerPoint.Presentation presentation = powerPoint.Presentations.Open(orginal);
presentation.Merge(target);
powerPoint.ActivePresentation.Saved = MsoTriState.msoCTrue;
}