private static string[] ExtractFiles(string sourceOddFileName, string sourceEvenFileName) { var oddFile = new PDFFile(sourceOddFileName); var oddPageCount = oddFile.GetPageCount(); var evenFile = new PDFFile(sourceEvenFileName); var evenPageCount = evenFile.GetPageCount(); var filenames = new string[oddPageCount + evenPageCount]; // Extract each page to an individual PDF file for (var i = 1; i <= oddPageCount; i++) { var pageNum = (i * 2) - 1; filenames[pageNum - 1] = $"temp-page-{pageNum}.pdf"; oddFile.ExtractPages(i, i, filenames[pageNum - 1]); } for (var i = 1; i <= evenPageCount; i++) { var pageNum = (i * 2); filenames[pageNum - 1] = $"temp-page-{pageNum}.pdf"; evenFile.ExtractPages(i, i, filenames[pageNum - 1]); } return(filenames); }