Marging 2 PDF Hello1 and Hello2 using Itext.jar

PdfReader reader = new PdfReader("Hello1.pdf");
Document document = new Document(reader.getPageSizeWithRotation(1));
PdfCopy copy = new PdfCopy(document,new FileOutputStream("HelloWorldPdfCopy123.pdf"));
document.open();
System.out.println("Tampered? " + reader.isTampered());
copy.addPage(copy.getImportedPage(reader, 1));
reader = new PdfReader("Hello2.pdf");
copy.addPage(copy.getImportedPage(reader, 1));

System.out.println("Tampered? " + reader.isTampered());
document.close();