[Solved] ASP.Net Convert.ToInt32 Error: Input string was not in a correct format

When i insert record into database from GridView below error is come

Input string was not in a correct format.

on below line

int inv_id = Convert.ToInt32((row.FindControl("Inv_ID") as Label).Text.Trim());

Means that last row, in which i display total, it does not have ID, insert query also try to read it then error occur, so how to prevent to go on last row where i display total.

        protected void btn_Save_Click(object sender, EventArgs e)
        {
            foreach (GridViewRow row in GVFood.Rows)
            {
                LoadRecordID();                
                int inv_id = Convert.ToInt32((row.FindControl("Inv_ID") as Label).Text.Trim());                
                TextBox txtRec_amt = row.FindControl("txtRec_amt") as TextBox;
                int cus_id = Convert.ToInt32((row.FindControl("Customer_id") as Label).Text);
                int item_wt = Convert.ToInt32((row.FindControl("item_Weight") as Label).Text);
                //  DropDownList ddl = row.FindControl("ddlStatus") as DropDownList;

                if (!string.IsNullOrEmpty(txtRec_amt.Text) )
                {
                    Insert(Convert.ToInt32(txtRec_amt.Text.Trim()), inv_id, cus_id, item_wt);
                }
            }
        }