https://blog.gongquiz.com/2021/04/11/%eb%8b%a4%ec%9d%8c-%ec%a4%91-csg%ec%99%80-%eb%b9%84%ea%b5%90%ed%95%9c-b-rep%ec%9d%98-%ed%8a%b9%ec%84%b1%ec%9d%b4-%ec%95%84%eb%8b%8c-%ea%b2%83%ec%9d%80-%ec%bb%b4%ed%93%a8%ed%84%b0%ec%9d%91%ec%9a%a9/