// Instantiate the Workbook object
            Workbook workbook = new Workbook();
            //Set value to Cell.
            workbook.Worksheets[0].Cells["A1"].PutValue("Hello World!");

            workbook.Save("pdf1.pdf");

            // Save as Pdf format compatible with PDFA-1a
            PdfSaveOptions saveOptions = new PdfSaveOptions();
            saveOptions.Compliance = PdfCompliance.PdfA1a;

            workbook.Save("pdfa1a.pdf");