How to Displaying serial number in DataGrid

<%@ Import="" namespace="System.Data" %>
<%@ Import="" namespace="System.Data.SQLClient" %>

<script language="VB" runat="server">

Sub Page_Load (sender as object, e as eventargs)

Dim con as new SQLConnection("uid=sa;database=pubs")
con.open()
dim cmd as new SQLCommand("select title,type, price from titles",con)
dim dr as Sqldatareader
dr = cmd.ExecuteReader()
datagrid1.datasource = dr
datagrid1.databind()
dr.close()
con.close()

End Sub

Sub populateSerialNumber(sender as object, objargs as DataGridItemEventArgs)
If objArgs.Item.ItemType <> ListItemType.Header Then
objArgs.Item.Cells(0).text = objArgs.Item.datasetindex + 1
End If
End sub
</script>


<form Runat="server">
<Asp:DataGrid Runat="server" id="datagrid1" OnItemDataBound = "PopulateSerialNumber">
<Columns>
<Asp:TemplateColumn HeaderText="S.No" ItemStyle-HorizontalAlign="right">
<ItemTemplate></ItemTemplate>
</Asp:TemplateColumn>
</columns>

</Asp:Datagrid>
</form>