https://blog.faceutil.com/2020/08/03/%ec%9c%88%eb%8f%84%ec%9a%b010-%ec%9e%83%ec%96%b4%eb%b2%84%eb%a6%b0-product-key-%ec%b0%be%eb%8a%94-%eb%b0%a9%eb%b2%95-windows-office-%d1%8e/