How to Open PDF document in asp.net web page without asking save/open/cacel dialogue

System.IO.FileStream fs = new System.IO.FileStream(Path+"\\"+fileName, System.IO.FileMode.Open, System.IO.FileAccess.Read);
byte[] ar = new byte[(int)fs.Length];
fs.Read(ar, 0, (int)fs.Length);
fs.Close();

Response.AddHeader("content-disposition", "attachment;filename=" + AccNo+".pdf");
Response.ContentType = "application/octectstream";
Response.BinaryWrite(ar);
Response.End();