Read more than one pdf file (iTextsharp)

static void Main(string[] args)
{
    string fileName = "test.pdf";
        StringBuilder text = new StringBuilder();
    StreamWriter write = new StreamWriter("test.csv");
        if (File.Exists(fileName))
        {
            PdfReader pdfReader = new PdfReader(fileName);

            for (int page = 1; page <= pdfReader.NumberOfPages; page++)
            {
                ITextExtractionStrategy strategy = new SimpleTextExtractionStrategy();
                string currentText = PdfTextExtractor.GetTextFromPage(pdfReader, page, strategy);

                currentText = Encoding.UTF8.GetString(ASCIIEncoding.Convert(Encoding.Default, Encoding.UTF8, Encoding.Default.GetBytes(currentText)));
                text.Append(currentText);
                pdfReader.Close();
            }
        }
         text.ToString();
    write.Write(text.ToString());
    write.Close();
    Console.WriteLine(text.ToString());

}