File Upload with specific file type

In apx page take label controls to display the message, File upload Control and Button

   <asp:Label ID="Label1" runat="server" ForeColor="Green"></asp:Label><asp:Label ID="Label2"
            runat="server" Text="Label" ForeColor="Red"></asp:Label>
        <asp:FileUpload ID="Fieldupload1" runat="server" />
        <asp:Button ID="btn1" runat="server" Font-Bold="true" ForeColor="DodgerBlue" OnClick="Upload"
            Text="Upload " />

In code Behind Under button click use this code,

 protected void Upload(object sender, EventArgs e)
    {
        string fileName = Fieldupload1.PostedFile.FileName;
        string exe = Path.GetExtension(fileName);
        if (exe.Equals(".gif") || exe.Equals(".jpg"))
        {
            string path = Server.MapPath("~/");

            Fieldupload1.SaveAs(path + fileName);
            Label1.Text = "File Uploaded successfully";
          

        }
        else
        {
            Label2.Text = "please Upload .gif or .jpg file";
       
        }

    }

Thanks & Regards