ค้นหาจำนวนผลิตภัณฑ์ที่ Sony ไม่ได้ผลิต
Find number of products which Sony does not make.
manufacturers_df = pd.DataFrame(columns=['code', 'name']); products_df = pd.DataFrame(columns=['name', 'Manufacturer'])
products_df[~products_df['name'].isin(products_df[products_df['Manufacturer'].isin(manufacturers_df[manufacturers_df['name'] == 'Sony']['code'])]['name'])].shape[0]