https://blog.gongquiz.com/2021/08/26/9%ed%8e%b8-%ec%98%86%eb%8f%8c%eb%a6%ac%ea%b8%b04%ec%bf%a0%ec%85%98-%ec%99%84%ec%a0%84%ec%b4%88%eb%b3%b4-20system%ec%9d%84-%ec%9d%b5%ed%9e%88%eb%a9%b4-40system%ec%9d%80-bonus-%ec%99%95%ec%b4%88/