read excel cell value in C#.net

if (!Page.IsPostBack)
            {
                Excel.Application appExl;
                Excel.Workbook workbook;
                Excel.Worksheet NwSheet;
                Excel.Range ShtRange;
                appExl = new Excel.ApplicationClass();
 

                  //Opening Excel file(myData.xlsx)
                workbook = appExl.Workbooks.Open(Server.MapPath("myData.xlsx"), Missing.Value, Missing.Value,Missing.Value,Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value,Missing.Value, Missing.Value, Missing.Value, Missing.Value);

                NwSheet = (Excel.Worksheet)workbook.Sheets.get_Item(1);
                int Cnum = 0;
                int Rnum = 0;
     
                ShtRange = NwSheet.UsedRange; //gives the used cells in sheet
               
                  //Reading Excel file.
               //Creating datatable to read the containt of the Sheet in File.
                DataTable dt = new DataTable();
                dt.Columns.Add("ID");
                dt.Columns.Add("Name");
                dt.Columns.Add("Status");
                dt.Columns.Add("Contact");

                for (Rnum = 2; Rnum <= ShtRange.Rows.Count; Rnum++)
                {
                    DataRow dr = dt.NewRow();
//Reading Each Column value From sheet to datatable Colunms                  
                    for (Cnum = 1; Cnum <= ShtRange.Columns.Count; Cnum++)
                 {
                       dr[Cnum - 1] = (ShtRange.Cells[Rnum, Cnum] as Excel.Range).Value2.ToString();
                    }
                    dt.Rows.Add(dr); // adding Row into DataTable
                    dt.AcceptChanges();
                }

                workbook.Close(true, Missing.Value, Missing.Value);
                appExl.Quit();

                 gvOne.DataSource = dt;//DataSource to GrigView(Id:gvOne)
                gvOne.DataBind();
      }